Had to or did change apple ID as it was my discontinued email address. The server is shutting down.

After more trial and error last night it seems the issue may be that the IPhone was registered and PW etc set on the Canadian site.
My IPad is registered and PW set on US SITE .

When I go on app store my info is recognized on IPhone and all is well. If I do same on IPad my old email address shows up(even though it has been changed at source)(new id shows up on iPhone) then iPad will not recognize old or new PW that does work for app access on phone.

I can't seem to be able to get new apple I'd that shows up on phone OK To show up on iPad .
Still clear as mud??

Thanks for any input that can resolve this issue