I encountered this issue on one of my forums. One of the admins edited the sidebar sections, thinking it would only customize his own sidebar. It changed the sidebar for everyone and I needed to fix it later.
When you edit a section, for example Community, there’s no mention anywhere that the modification is global and not applied only to the current user. The user being an admin, he didn’t know the edit button didn’t exist for regular users, who have a New Topic button instead of an Edit Section button.
Here I’m showing the “Make this section public and visible to everyone” checkbox like we do in custom sections, but it can’t be deselected. On hover/tap a tooltip appears to clarify that this section’s content is always public.