For anyone interested:
Sometimes I think it's easier for people to undersand when they hook up a Y connector to a gain channel then plug in a spare servo to see what the switches are doing to the channel output. It is easy to visualize that with a servo if you don't have a digital device to see the servo output pulse. I did such that for passing info on setting up a single channel gyro on an airplane.
FYI, this is for a single channel gyro but 2nd video @ 4:41 shows setting up gains on a DX7 flap channel for 3 positions.
Guardian OFF condition is full -100% (full CCW on the servo dial), Mid gain is 0 and full gain is +100 so think about that when looking at the short segment on the video. The area on the dial that shows "rate" would be like a "low gain" setting and the area that is on the right that shows "HH" would be HIGH gain setting. Further to the right is a higher remote gain value/multiplier.
This of course if you are not using your flap channel for something else.