Личное сообщение:

Sorry, but no; it doesn't answer any of my questions at all.

1.) Why are you posting in russian, linking a german link of the FAQ in the English part of the forum?
So are you somehow assuming the owners of the MuseScore company are reading along here? If so, consider at least posting russian translations into the russian forums. But if it is any consolation, those people are all quite decently capable of reading English and usually don't browse the forums of .org (as those are a community effort mostly).

2.) Why do you think you can't exercise your right of ownership on your scores?
None of the things you've linked explain anything about why you think you can't exercise your right. Unless you somehow came here to complain about your scores being plucked off of the internet by some random person and you having placed those scores on the internet yourself. The notation software doesn't magically does that on its own.
Or perhaps you have some issues with that score sharing website (musescore.com)? In that case, read on a bit longer in the faq you've linked to find https://musescore.org/en/faq#faq-20657 which further links to https://musescore.org/en/node/277874 (although all of this mostly links back to question 1 though... Why are you posting this thing here?)

So the only "putting two and two together" that this leads me to is that you seem confused about the two sites with a similar name. No worries, this happens time and again and we (the community) have been asking them (the company) to make the site headers more distinct so it is more clear on which site you're posting. Again though, the linked FAQ should clear that up for you.