App Store log in

I’m already logged into my App Store with the right Apple ID (the ipad used to be my dad’s so I had to log into another one) but when I update my apps it tells me to type my Apple ID password so I did but it tells me the Apple ID or password is wrong, I changed it (password) and tried again but it was still wrong (at this point I knew the Apple id was wrong but there was no button for me to change it) so I pressed the forgot password which goes to a page where it tells me to type my Apple ID but it automatically filled in my dad’s Apple ID but both my iPad and App Store was logged into my Apple ID, I tried to change it (the part where it automatically filled in my dad’s Apple ID into the new one but it just tells me to change my password at last, after I change my password it’s the same problem again, it just tells me either the Apple ID or the password is wrong but it wouldn’t let me change the Apple ID so what can I do?