Respondus 4.0 users simply need to use the "Check for Update" feature from within Respondus. Select "Help" from the menu bar, click "Check for Update", and click "Get Update".

For automatic update checking, one can go to Respondus->File->Preferences->General tab to enable "Automatically check for program updates".

One can also go to "http://www.respondus.com/download/respondus40patch.shtml" to manually download and apply the latest update.