I finally found the answer. It actually had to do with the Page Settings. I have now learned that if you want to give someone access to edit Module settings, you give them editing access to the page! To turn off access to Module settings, don't give them page editing permission.
It's a universal truth of Module settings ... good to know...
So, in my case, I gave only Admin editing rights on the page and not Editors. Then, on the Events Module instance, I gave my Editors the "Edit Module" permission. That allows my Editors the ability to add, modify and delete events on the calendar, but not to change the Events Module settings in any way.
Yay!