How to use multiple github accounts on macbook?

Question

git

When first configured, git populated the global config.

[user]
  name = Ivan Ivanov
  email = [email protected]
[color]
  ui = auto

Then I created a new repo and registered a local config for it with the same name, but with a personal email. I sent a commit to this repository, switched to another repository where, in theory, the global config should work. I'm trying to commit - I get a Permission denied message for a user from the previous repo (for which I set the local config). Why is this happening?