How can I stop the screen from switching to a noisy classmate who forgot to mute themselves?

I continually have problems in online classes where a clueless person has forgotten to mute themselves - so every time they cough, the screen switches to them.  This happens in a martial arts class where I need to see only the teacher at full screen at all times.  How can I stop the screen from switching to Mr. Clueless?  (Note:  I am not the teacher, I'm just a participant.) People don't read chats I send, so I have to interrupt the teacher to tell him to mute this person.  I have this problem a lot and I'm surprised it's so hard to find an answer.  It's super-annoying.