After updating to iOS 7 I discovered that the Messages app on my iPad was reset to use my iCloud AppleID. My iPhone, which was updated at the same time, retained my preferred AppleID which is tied to my primary and secondary email addresses—allowing friends to contact me using the addresses they know.
I was able to log out of my iCloud ID without difficulty but am unable to get the device (or service) to accept the password for AppleID I want to use. Again, this ID is up and running fine on my iPhone.
My preferred ID is also tied to my iTunes Store account and purchases from my iPad are working fine—seemingly eliminating "password" issues as the source of my difficulty.
Has anyone experienced this and found a solution?