Reply to EFX Reset

Hey there guys,
I saw a video for creating a build effect

But there was a cool setting that the instructor did, where when you turned the knob the group settings would jump back to their original settings.
For example, if you changed the FX from a delay to a reverb and changed the settings, but then you moved the man FX knob your original settings would, reinsert all the efx associated with that control.
I'm sure I missed something in the video, but if some one could point me in the right direction on how to do this I;d really appreciate it.

Many thanks in advance.