The instructions for the modded firmware say, "The menu only works while recording In preview the stock firmware owns the buttons, so the mod can't use them there. The easy way: start a short throwaway recording, set everything up, stop, then capture for real. Settings are saved and survive a power cycle.."
Are you perhaps attempting to change things while not in recording mode?
Annnnnnndddd... you were right! I honestly thought I had done it correctly, but what I did was start the recording, the perform what I thought was a "pause" - it clearly isn't just a pause like a VCR or audio tape pause. Once the machine is actually scanning, I was able to make those adjustments as you suggested.
Thanks!
John