We are building reports that allows us to navigate or drill down into the details. I can add navigation, but how do you edit navigation? What I have found is you highlight the report, then on the bottom half of the screen there are some tabs. One of them is navigation. According to the documentation is says you edit it there. There is nothing on that tab, yet when I use the navigation it works, I just have more than I wanted as I created new ones since the old ones were not listed.
One lesson, if you create the navigation it will not show up if the report is not assigned.