Razmee209 you need to read the question that has been posted above. Marine21 isn't trying to MERGE two Apple ID's, he has logged into the 'Manage my Apple ID' website and changed his PRIMARY email address on the existing account to another email address. If you click https://appleid.apple.comand log in you will see what he is attempting. Quit sitting on forums answering questions where you are misinformed, it just makes it harder to get a straight answer.
To answer your question Marine21, there is a very good chance that across your device you will have missed one of the login credential settings whereby it requires you to sign out and sign back in. For me, I ran into the issue with the 'Find My Friends' App. You could try restoring the device and then NOT restoring your backup file. Sync your data to the device separately once you have gone through the initial setup process. Alternatively, open your Settings app and make sure that the following sections have been signed out of.
- iCloud
- Messages
- FaceTime
- iTunes & App Stores
- Music (home sharing)
- Video (home sharing)
See how that goes 🙂 Good luck!