I was pushing and pulling from git in Terminal then I changed my username on github.com. I went to push some changes and it couldn\'t push because it was still recognizing
You probably need to update the remote URL since github puts your username in it. You can take a look at the original URL by typing
git config --get remote.origin.url
Or just go to the repository page on Github and get the new URL. Then use
git remote set-url origin https://{new url with username replaced}
to update the URL with your new username.