I just discovered that repeated edits of multiple events from a search list don't "take". I had searched for all WILL events, then went down the resulting list looking at each event (by double clicking on the event in the event search list). When I found a will event which had an executor which was a principal role, I would remove the principal roll check and then go BACK to the list (without closing that event window) and double click on the next event to move on down the list.
I subsequently discovered that none of my umpteen edits had been recorded. You must CLOSE the event window in order for the event changes to take place. I had incorrectly assumed that the process of moving back to the event list and double clicking on a new event (the most efficient way to process numerous events) would be sufficient. I'm sure the answer is that this is a deliberate program feature for some reason or other - but it certainly is not intuitive to me that the program should work this way.