GitHub, PhpStorm and SSH-key

If you can't push commit (or active branch) to github from PhpStorm, then check, how your repository was cloned in PhpStorm.
In repository folder find .git folder, there will be file with name "config" (without extension).
Check there [remote "origin"] section, if url starts with https, then you should change it to ssh-link (can be found on your repository's github page, looks like "git@github.com:username/reponame.git").

To check, if your SSH-keys is used properly, you can open GitBash and enter following text:
ssh -T git@github.com

Keys is always pair id_rsa and id_rsa.pub, you can't change keys in PhpStorm, you can only generate and upload public keys to github from each workplace.