It's a pain having to re-enter credentials every time you want to push to a remote repository via https. There are a number of ways to save your credentials, but perhaps the quickest and easiest name to store your username is to simply add something like this to your .gitconfig file (probably located in your root directory):
[credential "https://github.com"]
username = your_username
I also strongly suggest checking out the git credentials documentation. It goes into more detail about how this works and it describes a few other ways to store your credentials.
