Scale Percentage in TABs Staff/Part Properties - Bug
I think this is a bug, in TABs. The "scale" reverts to 100% if some other parameters are also changed.
To reproduce the issue:
1 - start a score and select guitar with TABs from the templates.
2 - in the score control click (Mac) on the TABs and from the menu select "Staff/Part Properties"
3 - in that new window, under "Staff Properties" change the scale to anything but 100% - let's say 120%
4 - now, click on "advanced style properties" and in that new window change the font size, lets say to 7.0pt
5 - click OK to close the "advanced style properties" window (at this point note that the scale percentage is still 120% as you've done in step 3.
6 - click OK to close the "Staff/Part Properties" window
Now you are back in the score, but you can see that the scale did not change in the TABs. So, now repeat step 2 and you will see that the scale jumped back to 100%.
You can only change the scale if you don't also try to change any of the "advanced style properties" at the same time.
Same happens in the standard staff. If you change scale percentage and at the same time try to change any of the "advanced style properties", the scale will stay at 100%.