Hi,
Look for a device menu button on the lower left of the screen (on the device itself) that looks like two pieces of paper. If you long press on that icon while in Touchdown do you get an menu? The Galaxy S5 button is contextual. Long pressing on it will show a menu that will be specific to the application you have open. Let me know if this helps. Thanks!
If you don’t see any icons on the device below the screen, make sure you have Touchdown HD installed and not Touchdown for Smartphones. Touchdown HD will have a soft menu button. Your license will work for either program.