How to resolve iPhone password loop problems?

Trying to update but I can’t because it keeps bringing old email which I don’t use and will either say wrong password or email and when I try forget password it just put me in a loop of getting code saying incorrect code and bring me back from the start

[Re-Titled by Moderator]

Original Title: Trying to update a app and my iPhone keeps bringing old email and when I try forget password he just put me in a loop of getting code and still say incorrect