My iPhone uses a 2nd Apple ID for the sole purpose of syncing to i Cloud(only because when apple introduced Mobile Me I signed on). I use another apple id for all iTunes and app purchases. When I set the watch up it automatically wants to use the @me.com ID, however I don't want to use that ID because none of my apps or music is connected to that ID. I also can't receive any of my messages on the watch because I don't use the email address for my iMessages. I did disconnected the watch from the phone and synced it back. It only sees my 2nd ID and won't let me change it.