Southern hospitality is no joke. Arriving in Nashville, it’s as though I’ve stepped into the animated portion of a previously live-action existence. Everyone I meet whirs with a rootin’-tootin’-how-ya-dootin’ folksiness that makes me feel both cared for and slightly car sick. In the taxi from the airport I say: “The weather is nice,” and the cab driver says, “Well thank you, we aim to please,” as if the locals had conferred and agreed to make it clear skies and 24 degrees. On my first night at a honky-tonk bar, a wasted hockey fan throws both hands on my shoulders and leans right in so my nose brushes against his. I feel certain he’s going to punch me in the face until he whispers: “Listen, I can tell you’re not from around here so I just gotta say, you have to try the fried bologna sandwich, you won’t have tasted nothing like it.”

Hayley Williams, Paramore’s lead singer and only continuous member, moved here when she was 13 after her mum and stepfather divorced. During the band’s early pop-punk phases she was known for her ever-changing hair colour and Hot Topic get-ups but today she bounds into the bouji brunch place she’s chosen with platinum blond hair and a fitted leather jacket. She could easily be mistaken for one of the modern country stars that flock to the city each year to record in its famed studios.

Paramore formed when Williams was 15. She’s now 28 and, basically, those intervening years have never been smooth sailing. Oddly, for a mainstream-focused rock band with a wholesome Christian background whose musical output is relatively uncontroversial, the band seem constantly embroiled in some huge internal fracas; it would be impossible to recount Paramore’s various bust-ups and reconfigured lineups in the Guide’s tiny pages.

Their eponymous fourth album, released in 2013, was an unprecedented success: it went to No 1 in the US and UK, secured them a co-headline slot at the Reading and Leeds festivals, and won them a Grammy for the single Ain’t It Fun. They had become one of the biggest bands in the world, yet it was hard to get past a bitter open letter that Williams’s guitarist ex-boyfriend Josh Farro and his younger brother, drummer Zac, had released on his blog in 2010. Both left the band citing Williams and the label’s controlling behaviour. One of the most stinging accusations was that her dad “would constantly threaten to ‘pull the plug’ on the whole band if we complained about anything, suggesting that we were hired guns … riding on the coattails of ‘Hayley’s dream’”.

Two years ago I asked Taylor if we could start a new band. I was so sick of this crap Hayley Williams

The remaining members – Williams, bassist Jeremy Davis and guitarist Taylor York – were struggling but told the Guardian at the time that the new lineup “was the best thing that could have possibly happened” and that they were now happy and settled as a band. It seemed as if their sagas were finally coming to an end and a new era as a triumphant triumvirate had begun.

But things didn’t work out that way. Two years ago, Davis quit the band and is currently suing them in federal court for a greater share of royalties and touring revenue. He claims that Williams agreed that the three of them would share authorship for all 17 songs on the last record. When it came down to it, Williams and York were credited as songwriters on every track with Davis only getting a credit on Interlude: Holiday, a 70-second banjo ditty.

Taylor York has stuck by the band and, seven years after quitting, Zac Farro is now back in the fold. Both follow Williams into the restaurant, and as we sit around eating omelettes and comparing caffeine addictions, you wouldn’t ever know there had been any animosity among them.

At one point, Farro’s youngest brother, Jonathan, FaceTimes him to say he’s having another baby. Farro can’t believe it. He’s screaming. He passes the phone to me. “Mazel tov,” I say. He passes the phone to Williams. “APRIL FOOLS!” screams Jonathan and everyone falls about laughing. That’s the vibe here: people who are so comfortable with each other that their siblings can punk them with fake news.

Famous five ... Hunter Lamb, Josh Farro, Hayley Williams, Jeremy Davis and Zac Farro in 2006. Photograph: Ralph Notaro/Getty

But how? How can you be so chummy with people you publicly insulted after a huge bust up? The Farros’ open letter accused Williams’s father of bullying members of the band and slammed Williams for writing ungodly lyrics. Was that all a lie? Or does Zac Farro think it was all true at the time but that things have changed?

He brushes that all away by insinuating he had less to do with the letter than it might have seemed. Farro was only 20 at the time and somewhat blames his older brother for the way things went down. “I’m a very loyal person to my family and I love them to death,” he says. “I stuck with Josh in a lot of things that I didn’t necessarily have as much of a say in as he did … some would say I lived in his shadow a bit and around that time [the open letter] came out I was realising that. How we were approaching leaving the band came across very differently.”

The other two members nod supportively, suggesting that it was Josh rather than his little brother who had the biggest problem (they also hasten to add that Josh has been very supportive of Zac rejoining). And Farro says it also feels as if the furore happened in another lifetime. “It’s like that podcast Serial. You know the first one with Adnan [Syed]?” he asks. “It opens up and it’s like: try to remember what you did when you were a teenager, try to remember what happened at 10:30 in the morning on a Thursday. It’s impossible. Within a week, you forget what happens.”

So maybe the bad blood with Farro is a distant memory, but the absence of former bassist Davis still looms large. However, because of the ongoing legal proceedings, the band say they can’t discuss why he left, or the royalties dispute, in interviews.

“What I will say is that it’s such bullshit that we’re in a lawsuit,” sighs Williams. “I wasn’t OK for a while; maybe I’m still not.”

Taylor York says that he didn’t even feel Davis’s leaving because he was so used to the pain of Paramore. “I was just numb,” he says. “It was just another drama and another example of being in a band and it being really difficult, and feeling bad about that. We have the coolest job ever but why does it have to be so hard?”

Obviously, I say, it doesn’t have to be so hard. If being in Paramore is so stressful, why not just pack it in for good?

“Oh yeah,” says Williams, assuredly. “Two years ago I asked Taylor if we could start a new band. I was so sick of this crap. I said we should just try something new, give it a new name.”

York nods: “I’ve wanted to quit this band so many times. Going through all this conflict and drama over the years … I was just like: ‘Man, I feel like we can keep going, but this is not worth it if we don’t want to be here.’”

We’ve spent time crying together over things that we never dealt with Hayley Williams

So, if the only two remaining members wanted the band to end, why didn’t it? No one can give me a straight answer as to why Paramore ended up deciding to make another record.

“Honestly, I don’t know,” says Williams when I say there must be something, before making an attempt to explain. “We, for some reason, kept showing up and kept writing and, little by little, the songs got better and we got a little more inspired to do it.”

The songs they wrote together didn’t sound anything like the earlier emo iterations of the band. There are some you could see as an evolution of the poppier stuff on the previous album but, if anything, they owe more to the 80s rock of Paul Simon and Dire Straits. It’s not cheap 80s pastiche, though; the tracks are rich, smart pop that any megastar would kill for. In particular, first single Hard Times, with its Lionel Richie drums, heavily layered vocals and Daft Punk-style breakdown, you could easily imagine being their biggest hit to date.

Still, even with their old friend back and a fertile creative period, I’m frustrated by the band’s lack of explanation around what actually keeps going wrong. Even the song titles on the new record After Laughter: Forgiveness, Fake Happy, and Rose-Coloured Boy, with its refrain of “just let me cry a little bit a longer”, point to a band whose every day is a struggle.

Reading matter ... Hayley Williams on stage at Reading festival in 2014. Photograph: Isaac/LNP/Rex/Shutterstock

I push them on what infected their relationships. Their reticence to spill is partly, I think, the fact that they are all from this city, which, in public at least, seems like a place where if you don’t have anything nice to say you shouldn’t say it at all. Sometimes, that southern kindness can be a barrier to discussions about what’s really going on, something they admit has been an issue in the past.

“We grew up in a very conservative environment,” explains York, “where you always give people space because you don’t want conflict. So, if something pissed you off, you don’t talk about it.” But the biggest change in their lives is the most obvious one: age. The first 10 or 12 times Paramore had a bust-up, they were teenagers. When someone was unhappy they sulked or, worse, took to their personal social media channels to let their feelings be known. That open angst played a big role in the band’s success with their teenage fanbase but was also a sign that they didn’t have the wherewithal to handle things going wrong.

“If there is something intangible that none of us can place that’s different about this record, I sense that there’s a lot of acceptance of things not being … shiny,” says Williams. “We’ve all lost that teenage thing of trying to hold on so tight to someone, not realising you’re choking them. [When] you become an adult, you hold each other loosely, so everyone can show up as themselves. We’ve spent more time hanging out and laughing doing this record and equally crying together over things that happened that we never dealt with.”

That’s definitely a process they’re still living through, even in this interview: by this point, the brunch place has filled with bachelorette parties and we’ve moved to a more insular private room. It starts to feel like that bit in Mean Girls where everyone talks about their feelings.

Sometimes, the trio will revert back to empty platitudes about how good everything is. At one point, Farro says: “I used to be, like, ‘Wow, the future looks so far away’, now I’m, like, ‘I hope I can keep up because it’s right around the corner.’” But at other times, a kind of darkness boils over. I ask whether they think about what they’ll do when they’re, say, in their 50s, considering the band is all that they’ve known. That seems to throw them.

L’esprit d’escalier ... (left to right) Taylor York, Hayley Williams and Zac Farro. Photograph: Lindsey Byrnes

“If I envision my future, it’s really dark,” says York. “I just can’t even go there in my head. I know it sounds weird but I think I get enough anxiety and fear about tomorrow or this afternoon.”

Three hours after we first meet, it’s kind of tense in the room. They are really lovely and kind and say “thank you” for the interview, but it is apparent that for the band to work in the long run they can’t just pretend to be OK; they have to say what they actually feel.

“In the past, we’ve made it our mission to shove down people’s throats what we want them to see. You know: ‘It’s us three now, we’re doing so good!’” says Williams. “And I think we don’t really have that agenda any more. Oddly, I think we’re actually in a better place as a band than we’ve ever been. I think in the past this would have pissed us off. Not you, but this drudging through it; but I think now it’s, like, cool. It almost makes it less of a big deal because we’re not resisting it so much.”

Suddenly, they have to run off. They jump into Williams’s car and drive four hours to Atlanta where they’ve managed to snag Radiohead tickets. They’re not taking meetings or anything while they’re there. Just mates going to see a band. Williams emails the next day, telling me about their road-trip playlist and how hyped they were. “No Surprises was so rad to hear live,” she writes “because I remember listening to it, sitting on the back of Josh’s car with Zac and Taylor and a few other friends while we watched fireworks on the fourth of July in 2003.”

That’s when I understand why they are still plugging away with Paramore. Because the people still in the band, the ones willing to sit through interviews and work through problems, are the ones whose friendship withstood everything it was put through.

Paramore’s new album After Laughter is out on 12 May; their new single, Hard Times, is out now