I've installed the portable version. Well, just unpacked the zip, which portables usually are all about. But in addition to that, I've managed to associate the .mscz files with the exe, and Windows 10 nicely launches Musescore and opens the file.
But if I double click another .mscz file after that, Windows launches a new instance of the exe. That seems to happen also if I happen to click at the Musescore launch icon in the task bar. I guess this is a problem between Windows and the portable exe. Is there a way to teach Windows to not launch new instances of the exe?
OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (32-bit): 184.108.40.2068021803, revision: 3224f34