Resetting the Preference file worked--thank you! I am now able to move the measures between staves again. Thanks also for the warning about the "automatic" options. Thanks for the help!!
Yes, I have restarted the computer every day, with the same unfortunate result. In Edit / Preferences / Edit / , the Reflow Measures drop down window is set to "Across Systems (Remove System Locks)...
Yes, that was the problem. Thanks!