Not sure if this is a bug in the forum software so let me try to explain. On mobile there is an icon with three horizontal lines at the top left corner that contains some navigation options. When you click on any forum or message it changes to an arrow that lets you navigate back. What I think is a bug is that when you click the home icon the arrow is still there and you have to click it a few times to go back to that starting icon with the navigation options.
It's a bit weird. I'm trying to find a good way to use this forum and thought this navigation icon is a good place to start but I have to keep going back to see it.