can't change page settings of parts

I'm using musescore 3.0.0 (53d4ad2).
I can change (and have changed) the staff spacing of the main score, but I cannot
see how to change it for the parts scores. The menu item Format->Page Settings,
brings up a dialog displaying the main score, when I change the Staff spacing,
the Staff spacing changes for the main score, but the [Apply to all parts] button
is greyed out. Also If I display one of the parts, and use the right mouse button to
select [Page settings...], again I have the controls dialog for the main score, and no
way to change the staff spacing for the part.