I want to change my devices Apple IDs
I want to change my IMac, iPhone and iPad to another existing Apple ID. The actual process does not allow to change to an existing one.
[Re-Titled by Moderator]
What happens when you try to change to the other existing Apple ID? Error message(s)? More information would help.
Have you tried signing out of the Apple ID that is currently on the devices/computer, restarting, and then see if you can sign in with the other Apple ID?