Tempo Text anomaly

This is soooo not a big deal, but it is bugging me that I can't figure it out.

Background....
I'm new to Musescore (and loving it). I'm making practice scores for the Vaccai vocal exercises. I started out putting all the exercises in one big score with each exercise as a new section. About 1/2 way through the project I realized that I'd rather have one score per exercise, so I split the score up and started making a new score for subsequent exercises.

The anomaly...
In the big score - the first I ever created - (and all the scores that derived from it), tempo text appears on all the staves in the score - that is, when I select a note and click on, say, "Allegro" in the Tempo palatte, the text is inserted above both the vocal staff and above the piano grand staff (right hand line only). I didn't realize it at the time, but according to the handbook, this is NOT the expected behavior. The handbook clearly states "Tempo text always appears on the top staff of the system. If you need to see it on lower staves as well, use staff text and insert the beat note as a special character."

In all the scores I've created since that first one, the tempo text behaves as described in the handbook. I've reduced this to a minimal test case. I now have two test scores with one bar each. In one score the tempo text appears on all staves and in the other it appears only on the top staff. I cannot find any differences in the setting for the two scores. I've reset the Format->Style and Format->Page to the defaults.

Like I said above, this is not a big deal, but it is bugging the heck out of me. What in the world is the difference between these two scores? "test 1.mscz" shows the tempo text on all staves, "test 2.mscz" shows the temp text on only the top staff.

Thanks,
Tom