To mute attendees individually, mouse over their mic or telephone icon:


Important: Attendees will un mute themselves. You will not be able to un mute them.

To mute everyone that is currently in your meeting, click the icon at the top of the Attendee area called Mute All:


To have all subsequent attendees join muted, tick the box highlighted in red above.

You may also disable the chimes heard when someone comes in or exits by ticking that box: