Need to block enabling of audio and video as a host of meeting

As a host of a meeting, I need to disable audio and video for attendees and block them from enabling. I need to enable one at a time. I have tried in RC Meetings and in the RC app (newest versions). I found info in articles online including pics. Says to click on Participants and then there should be three dots at the top of the participant box. This menu has all the options I'm looking for, but my app (both desktop and mobile) does not have the three dots.