Apple ID and Password are incorrect error showing even though the information is 100% correct.

I'm seriously just trying to update a single app that I can't open if it isn't updated. I have made a new account, reset my password three times, restarted my device multiple times, and for the past two hours have been waiting for someone from Apple to finally take me off hold.

The password is correct, yet I cannot update this singular app. This is beyond frustration because it's just a tiny problem causing such a nuisance. After a few hours of trying and trying, now it's giving me an error that says to Open settings to continue signing in with... The email that pops up isn't associated with my device in any way or form. Could I get ANY sort of help with this issue?