Older Apple TV

If you have changed your ID or password, have you followed the steps in this article?

What to do after you change your Apple ID or password - Apple Support     

Suzq802:

"Older Apple TV: I’m trying to log into Apple TV but it keeps asking for my old email address and password"

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Rid of the eMail on Store and iCloud:

Are you able to rid of your old eMail address?

Remove it, then login using your new eMail address and password.