Echo sound

Im french and dont speak very well
hope you will understand my problem and help me to resolve

Usualy i give relaxation to people who cant pay in a club
With the covid, none of the participants can go to the room where we use to practice

a friend of mine told me about jit si

I have a big problem with the utilisation

2 times on 3 whe have an echo sound wich is very unpleasant and disturb all the relaxation because of the background noice it brings to participants

I have used the combination of FUNCTION + ESCAPE to swich of the micros of participants.

unfotunatly sometimes it works and sometimes not.
And I dont understand why

does anybody have a solution as I can continue tu help people proposing thoose free relaxations ?
thank you, take care of you