Our Support Team is ready to answer your questions. You can contact them via this link. Please do not forget to add a screen recording of the issue if you want to report a bug, it'll make your report more useful.
Also, you are always welcome to post a question or to report an issue on our mobile forums:
Android app forums may be found here:
https://musescore.com/groups/musescore-android
iOS forums may be found here:
https://musescore.com/groups/musescore-ios
If you have any questions concerning our notation software please post them at the forums.