You've been using iOS for ages and think you know what you're doing, but do you? These common iOS mistakes make you look dumb, so here's how to avoid them.

Wrong finger

You set Touch ID up to work with your thumbprint -- all the same when you try to approve a payment or purchase a tune you keep using your finger an it doesn't work. Annoying.

There's a solution:

Open Settings>Touch ID & Passcode and enter your passcode to access the next screen. Look to the Fingerprints section and you'll see Finger 1, below which you'll see the 'Add a Fingerprint...' option. You can enrol up to five fingerprints for Touch ID.

Bonus tip: If you share your device and trust the person you share it with, why not add their fingerprint too?

iOS security

You've set up passcode lock, Touch ID and have Find My iPhone enabled. You use a strong iCloud password and two-step verification.

You can do more:

Open Settings>Touch ID & Passcode. Atthe bottom of the menu you'll find 'Erase Data'. This is off by default but when enabled your device will erase all your data after 10 failed passcode attempts. If you care about your security you should use this -- particularly if your iPhone is also your credit card, thanks to Apple Pay.

Bonus tips:

Turn off Diagnostics and Usage Data (Settings>Privacy>Diagnostics and Usage, tap Don’t Send.)

Turn off Geo-Location for Photos (Settings>Privacy>Location Services>Camera, Never.)

Disable Location based Ads (Settings > Privacy > Location Services > System Services, toggle to Off.)

Limit Ad Tracking (Settings > Privacy > Advertising and set Limit Ad Tracking to On.) Also be sure to Reset Advertising Identifier so advertisers cannot track you using the ID you've used until now.

In Safari (Settings>Safari>toggle Do Not Track to on) -- and set the default browser to Duck Duck Go instead of Google.

Finally in Settings>iCloud>Find My [Device] turn on the Send Last Location option.

Now you seem much less dumb.

Slow phone!!!!

Some users have claimed their iOS device runs slower since they installed iOS 8. They moan about it so much you know that some of those complaining probably don't even use iOS!! It's funny - but all these complainers are pretty dumb, unless they've at least tried this fix:

Open Settings>General, select 'Reset' and then choose 'Reset All Settings'. This won't delete anything (bar your WiFi password) but might help mitigate performance problems.

Bonus tips:

Now read this for a bunch more useful iOS 8 troubleshooting tips.