You might be running a session that solely uses polling with no requirement for Q&A or a discussion. If that's the case you might want to disable this feature so your participants can't see the Q&A board on their mobile devices.
To disable the Q&A board:
When you are logged in, select Q&A from the navigation menu on the left.
Select the 'Features' tab in the pop up.
In the top messages menu bar toggle the Q&A ON/OFF switch.