Well I eventually saw that the Open Settings button in QGO does NOT open the regular Quest settings but another Android Settings app.
When I first saw it in the video and in my headset I thought it was just a squished view of the regular settings, which I wasn't able to un-squish, so I went there the usual way so I could see more settings at a time. Then I couldn't find any of the documented settings anywhere.
Then somehow I considered after reading a comment here about someone needing to install another package that maybe the QGO button was launching something different. Then, whoa, I saw that it in fact was an entirely different settings app on my headset.
After that I was able to follow the remaining directions.