How to ask for support
There are 2 sites: musescore.org and musescore.com and the same login works for both sites. They also share a common Help Center
musescore.org is the main site for questions about the MuseScore editor software, the free, open source desktop software (Windows, Mac, Linux...) and its support and documentation.
musescore.com is about sharing (also the Pro account) and discussion scores, also discussing the mobile apps (for iOS, Android, Fire OS). Also importing PDF and sending scores to YouTube belongs here.
For musescore.org there are several forums divided by categories:
While for musescore.com there are numerous discussion groups
including those dedicated to the apps