That's easy to solve too, go to account settings, scroll down and there appears your email
And if he forgot the password, at the bottom of the email thing there is something that says "password: exist" and click in change password, you don't need to verify the old password you just need to put the new one then click ok and that's it

have you tried deleting the app and installing it again? (if you don't want to lose your anime files you can back them up)