When a user clicks on a discussion they are taken to the full discussion. But the tag on the menu says 'Forum Home'. The users naturally think they are in Forum Home. It may be obvious to us that they are not but it isn't necessarily obvious to the user. You can't expect users to 'think'
Unless I am missing something here, I think this is very bad!
Clicking on "Forum Home" indeed takes you to the Forum Home, ie the main Forums page from which you can browse categories and recent forums.
However, if there's a different type of wording or terms you'd like to use, you can use the Language Editor (as described in this page in the help center) to modify the text to your liking.
When someone opens a discussion on Main it takes them to the full discussion page but the tab at the top says Forum Home. It starts off saying Todays Discussions, then changes to Forum Home.
This sounds like it may be an issue with your social network. Could you please contact us via the Help Center? It's easier for us to help you troubleshoot these issues this way.