can not change email or phone number no matter what i try. also, the email i used to sign in and the one listed in account details are 2 different emails?

i have no idea what's going on. the title is self explanatory. i sign in with one email that has NO OTHER ASSOCIATION with my account. i go into the settings, and the email that's listed in the account details page is a completely different one. i have absolutely no idea how this happened. i just need someone to tell me what's going on and how i can fix it. i need to be able to change emails, as they're all messed up and on the wrong accounts now.