Where does QS Store Interface Configuration?

[sclough]

Where does QS store customizations to the interface? I have my
interface customized, but some times I like to adjust settings and
even try new interfaces and adjust their settings. However, that means
I lose my current interface settings. I'd like to be able to back them
up and then if I make changes I can at least revert back to what I had
before without having to set it up again.