Echo & Reverb issues teaching yoga - hosting a zoom meeting on 2 devices

Hi,

I'm teaching yoga on my zoom account. I use my iphone as the camera on a tripod at the far end of the room so it captures my whole body.

Closer up I have my laptop where I can gallery view my students and make sure they are following ok.

I'm using the camera as the host to video (and also record) and also capture the audio.

So I log into the lap top after the phone is set up, and mute it.  I also go into settings on my lap top and mute the microphone.  But problem is I am still getting echo/feedback.

Any advice?  

I have earbuds which I'm not currently using either which I think would soften the audio but the whole thing is a bit of a mess at the moment! Thanks for any advice x