If you choose File> Clear All Settings, and then choose File> Restore Factory Defaults, this will bring your 18i8
back to its original factory state.
If you go to File> Save To Hardware, this is the state that your 18i8
will be in everytime it is connected and powered on (as well as standalone); regardless of what changes are previously made.
If you would like to save a particular MixControl template, I would recommend saving a "snapshot" that you can load when you are ready.
This can be done by going to File> Save ... and saving the current snapshot!
I hope this helps!
David // Focusrite Technical Support