Unintended Clef Change

I use SoundFonts Grand Piano to represent vocal parts because the note sounds are more incisive than Choral Ahhs. I have template files set up for this with SATB lines as pianos, with the clef appropriate for each. That means treble for SA, down-octave treble for T and bass for B.
Occasionally a piece has B1 and B2 parts, sometimes in different lines, sometimes as voice 1 and 2 on the same line. For difficult pieces, I add a B2 line to the file created from copying the template.
To do this, I go to Layout (MS 4.5.1) and add a new piano instrument, which comes in as MuseSounds->MuseKeys->Grand Piano, with treble and bass clefs. I delete the treble line using the trash can in the Layout dialog. Then I open the Staff/Part Properties dialog to change the title of the new bass line to Bass 2/B2.
In the next step, I forget which, either clicking Apply or clicking the up arrow to move to the B1 line, the clef marking on the B2 line, the new one, changes to treble. I will have to go back after updating the title of the B1 line and fix it. This is not new in 4.5.1 - previous releases also did it.
Of course this is not an urgent problem, but it is a long-standing one.

Has anyone else experienced this? Thanks -
RNW