For me and at least one colleague, it has happened that after we update the course navigation settings of our course, we forgot to save it. I believe an important cause for this is that the Save button is not visible unless you scroll down to the bottom of the page if there are many possible navigation options.

I believe the chance that a user will forget to save will be a lot lower if this button is moved to the top of the page, so it is always visible for the user when they enter these settings. Giving some warning to the user that they should save in case they make adjustments could be an alternative.