I can not sign in on iPad .
If I want to say....update an app. I klick on app. The little screen with apple I'd pops up and asks for password. The ID that shows up on iPad is old one. The password is not recognized ,therefore cannot buy or update app on iPad.

On iPhone doing repeat of above to upgrade app, my new apple ID (that I changed online )pops up and asks for PW. I enter new PW and app is updated as it should..

The pop up screen for apple ID and the PW is not the same on iPad and it will not work