Text Frame Options. Room for Side Heads added without warning

Hi -

I just got asked this and have no clue how to help. Anyone know what this is?

Every now and then, my Frame file will –apparently on its own – reset most of its text frames into having room for side heads.  Makes for lots of bad labels on graphics – everything’s suddenly offset and scrolling off the bottom.

This will happen suddenly.  It will usually be only one or two chapters in a book, but if I ignore it has been known spread like the black death throughout the book.

The only solution I’ve found so far has been to revert to a backup or touch each text frame individually.  Setting properties for two at a time messes up location on the page.