This is my config that I believe is that same one in the most recent official OS 0.5.
You can save a new config that will use the date as part of the file name. That way if you mess up, you can always reload your previous save file.
This is a great way to mess around with the config, and get to know how Retroarch works. When something works, save a dated copy. I even keep a backup of my clean config, in case I want to return to how things were originally.
In my custom DEOT image, I actually made a utility to recover the Retroarch config, almost like a panic button.