Thank you gents:
Thanks for your input; However, I solved the problem as follows:
The “default” presentation on my screen was the “Storyboard” display mode. In this mode, it will not let me add a second audio track (as you probably know.) It wouldn’t even display “Track 1” or ‘Track 2.” It only showed “Linked Audio.”
I “accidentally” selected the “Timeline” mode, and now it will let me add tracks as you described.
It is very irritating to me that I could not find any instructions from NCH describing these two modes. It took me three days of experimenting to figure this out