Check also your git config user.email
:
The email must be the one associated with your new account, not your old one.
(That is illustrated by a recent answer at "Git commits associated with old, defunct user instead of the user I have now")
And regarding the push, make sure your url isn't an https one with your old login in it:
htps://OldLogin@github.com/newLogin/newRepo
(type git remote -v to see the 'origin
' url)
If it uses an ssh url, then as mentioned, check your public key: