From within MuseScore, choose Help / Ask for Help, which takes you directly to a page where you can ask your question on the support forum.
From musescore.org, choose Support / Forum in the menu at top, then Forum, then "Support and bug reports", then the "Add new Forum topic" button (if you are not logged in, you will instead see a button asking you to do so first).
Comments
At least inside Firefox.
Step one: Select the forum and not the issue tracker.
More specifically:
From within MuseScore, choose Help / Ask for Help, which takes you directly to a page where you can ask your question on the support forum.
From musescore.org, choose Support / Forum in the menu at top, then Forum, then "Support and bug reports", then the "Add new Forum topic" button (if you are not logged in, you will instead see a button asking you to do so first).
I will address this issue by putting a button on /forum which is currently missing. It used to be there before the site upgrade in Aug last year.