System layout

I think MuseScore is a neat tool for writing music, and it has improved quite a lot since I first tried it out several years ago. However, there is one thing that drives me absolutely insane, namely that there seems to be no way of telling MuseScore to set a fixed number of measures per system, so that whatever that number is, those measures always stay together. You can of course decrease the system stretch to get more measures to fit on any one system, but that will only work to a certain extent. After that, you have to manipulate other layout settings, several of which at first can seem to have no effect, which just makes it all very confusing to me. The possibility to always keep a certain number of measures together exists in both Finale and Sibelius, and although I am by no means a skilled programmer, it seems to me it should be quite easy to achieve something like this.
I can attach a score, so you can see what it is I'm trying to do here. I have a score with 6 measures that I want to distribute over two systems (3+3 measures). So I tried setting a line break after every third measure, but instead of having two systems, I ended up with three (2+1+3 measures). What am I doing wrong?