Measure numbering question

There's basically two ways to achieve the same result. One is to exclude each of the first eight measures from the measure count (call this eight times zero), and the other is to leave them as they are, go to the next measure, and in the Measure Properties dialog for "Add to measure number" enter "-8" (call this eight plus negative eight). (8)*(0) and (8)+(-8) both equal 0, so you get the ninth measure counted as the first either way.

By the way, a useful tip: it's not necessary to "select each bar" one at a time. Once you're in Measure Properties for the first measure, you can use the arrows in the bottom left corner to go on to the next measure without leaving the dialog.

No way to exactly that, but you can simply reset the measure count in bar nine (Measure Properties / Add to measure count, set to -8). You can also exclude consecutive measure from the count more quickly than selecting each one by one: do itfor the first, but then with the Measure Properties dialog still open, hit Apply and then press just the right arrow button at the bottom of the dialog to move to the next measure. So you can exclude a whole sequence of measure by hitting Exclude, Apply, right arrow over and over. But I think just adding -8 to the count for bar nine is easier.

On this issue I seem to recall that earler versions of Musescore had a right-click function to enable the alteration of time signature in an opening or closing bar. It no longer seems to function - rendering the programme unsuitable for professional use. Maybe I'm missing somenting ...