WP-CONFIG - How can this get updated and not affect the theme

Hello,

I was just wondering if I wanted to change something in wp-config that I initially set up. Is is just a matter of going into an editor making the change and then just transferring it via FTP without affecting my activated theme? Like if I want to change the random keys or maybe the User Id password that I initially had when I set up wordpress? Is it possible even after you have started modifying your active theme?

Thanks!

Maria