Q: How to change Apple ID on the phone

Howdy FrankieWires,

While you may not have changed your Apple ID or password, the article linked below details all of the locations that you might have signed into your Apple ID on your iPhone so that you can sign out of your Apple ID where necessary.

What to do after you change your Apple ID email address or password
https://support.apple.com/en-us/HT204071

All my best.