How do I change my email on the App Store?
How do I change An email associated with the App Store?
Question marked as
Change information in Apple ID - https://appleid.apple.com/
Change your Apple ID - https://support.apple.com/HT202667 - "Follow these steps to change the email address that you use as your Apple ID."
What to do after [or before] you change your Apple ID email address or password - https://support.apple.com/HT204071 - "After you change your Apple ID email address or password, you might need to update your sign-in information with any Apple services you're using." - Or if you're seeing persistent disabled messages or repeated requests for the password to your previous AppleID.
If you didn't receive your verification or reset email - https://support.apple.com/HT201455