Mr. Trump’s personal account simply identifies him as “45th President of the United States of America.” The bio on the official account adds: “Tweets by @DanScavino. Tweets by #POTUS signed -DJT.” (Dan Scavino is the new White House social media director.)

So far, none of the official posts have been signed -DJT, even the one that reads, “On behalf of my entire family, THANK YOU!”

At one of his inaugural balls on Friday night, Mr. Trump joked about whether he should give up his regular use of Twitter, making it plain in his punch line that he had no intention of doing so.

“Let me ask you, should I keep the Twitter going or not?” he asked the revelers. “Keep it going? I think so. I think so.”

Mr. Trump and his aides have long said the president values his large social media presence for its ability to give him a direct channel to his supporters.

As Mr. Trump put it at the ball: “You know, the enemies keep saying, ‘Oh, that’s terrible,’ but it’s a way of bypassing dishonest media, right?”