Need help fitting all to one page

Press Ctrl+A which will select everything, then press { to shrink all measures so that the last two measures will fit on the first page.

Regards.

This is exactly the place to post. Welcome to the forums!

You'll want to decrease stretch a notch or two—see https://musescore.org/en/node/35896#ways-to-affect-layout. The simplest way is to select everything and press [ { ].

In general, you reduce stretch to fit more measures into a line, and use line breaks to make it be fewer. A combination of the two techniques—adding line breaks at the end of each line, and then reducing stretch—is a good way to make sure that the score will be laid out the same in future versions of the software.

Also, you wrote: "In the older versions, there was an option to choose the precise amount of measures per system..."
To set a fixed number of measures per line use menu item: Edit -> Tools -> Add/Remove Line Breaks...

Regards.

Actually, there was never any setting that allowed you to choose the precise number of measures per system. The option in 1.3 and earlier only allowed you to choose a *maximum* number of measures. But setting it higher would never cause MuseScore to fit *more* measures per line than it otherwise would by default given your current spacing settings. So it was just a crude and much more limited version of what 2.0 providees as Edit / Tools / Add/Remove Line Breaks.

Overall, I think you'll find the layout is greatly improved in 2.0. See for instance https://musescore.org/en/node/25102. Sometimes this will mean scores will fit more music on a line than they would have in 1.3, sometimes less, mostly it will be the same, but the layout *within* those lines will in virtually all cases be better. And the options for controlling the layout are more plentiful and powerful. But it does indeed occasionally mean a 1.3 score will look different loaded into 2.0.