I created a new gmail address for an Android phone a couple of years ago. It used the googlemail.com domain rather than gmail.com as Google was having a bit of bother at the time. More recently I was told by Google that I could use the gmail.com domain instead of the googlemail.com domain as the 2 addresses were linked, which I did and distribute my address now as ----@gmail.com
There are legacy logons and email addresses stored here and there that still use the googlemail.com. In the worst case I can delete these and created new accounts or whatever.
But how do I make the change with the phone itself? I've associated my @gmail.com address to my phone but it co-exists with its googlemail.com twin. When I tried to delete the twin I was warned that all data relating to that account would be deleted. I have disabled sync for it but still get annoying notifications that there was a problem logging in as it's waiting for my password.