How do I formally submit a bug report and/or a feature to be added?

Title says it all. We've discussed, on the forum, the bug where CTRL-Shift-hyphen does not add a non-breaking underline to a lyric, but rather a non-breaking em dash.

I would like to have that corrected. Failing that, it would be nice if a key (Shift, maybe?) would constrain a line to horizontal, when dragging or resizing it.

Finally, how can I tell if my requests have been accepted and assigned?

I've attached a MSS file that may better explain the problem. The last entry I can find on the topic was five years ago!
https://musescore.org/en/search/content?keys=site%3Amusescore.org%20hor…