Q: My email user id is no longer valid but cannot the iPhone 5s will not allow  me to change it.

iTunes uses the same user id as iCloud but it is not showing it on the new iPhone 5s, IOS 9.3. I downloaded the wrong back up onto the new iPhone from an iPhone 4, IOS 7.1.2 but cannot find a way to go back and use a more recent backup with the correct user id email address. The old email address is no longer active so cannot find a way to get into iCloud, turn off "Find my iPhone", reset or "Erase all content and Settings" to start over with the newest back up. It only gives me the old email address as the user id and even though the password was the same the email is not longer active.