To turn on their camera and/or microphone, select Request Control. A pop-up will appear on the attendee's screen, asking him or her to grant you access to their mic and camera. If they approve, you'll then be able to turn their microphone and camera on or off. (Note: This feature is only available for attendees who have already turned on their cameras. If the attendee hasn't turned on their camera during the session, you cannot request access to it.)