Setting up new phone - backup asks for wrong apple id

I recieved my new iPhone 6s plus and am setting it up from back up. After I select the backup... It then asks me for a password to a different Apple ID (different email address) that had been changed to the new email (for same account). The email is no longer on the account and has no Apple ID associated with it. The backup is from two days ago so I'm so confused. Please help!