I noticed that not only does one have to check the checkbox beside a grouping in the left column of Condensing Change; one also must highlight the instrument names in light blue to see the switches in the right column. That gave me a run-around for a while before I happened onto what I needed to do. I had supposed that I needed only to check the checkbox to activate the switches (and I was referring to the Version History all the while), but I can see now the need for both checking and highlighting to allow for multiple changes in a single pass.
Thought I’d mention that in case anyone else has been (or will one day be) confused about it.