Tempo marking on all lines

Hi, I was surprised when I applied a tempo mark to this score that it appeared on all lines, as in the attached screen shot. I tried some other scores, and there the marking appeared above the top line only, as expected. The peculiarity of this score is that the alto "line" actually contains two lines, hence 'Alto' written between the two and the tempo marking appearing above the upper of the two.

Best,
Andrea
(on Mac, OS 14.7)