Sometimes, you try to push you local repo:

git push

but obtain the following error:

remote: Permission to username1/repo.git denied to username2.
fatal: unable to access '':
The requested URL returned error: 403

That's because you need to change authorization info from Keychain. To do this by:

git config username2
git config name2@email

git config credential.username username2

After this, git will authorize by username2, and you will see the credential section in git config:

        username = username2