Changing default associated facebook log in? HELP!

Hi everyone,

Checked everywhere on google for this but couldn't find fix.

Broke my Iphone X, currenty borrowing a 6S instead, wanted to log into an app (hinge) that only lets you log in via the facebook log in assist. The iphone is by default trying to log in with the persons facebook account who's phone it is. I cannot see anywhere in settings how to change it from doing this - I thought it might be associated within the app itself so I have removed their log in from the app to leave only myself saved on it, leaving my account logged in - however still everytime when I launch hinge it says do I was to continue via facebook under their account. Is there something i am missing? Do I need to change something in the phone settings itself?

Thanks for any help.