Zoom on MacBook Pro

Hi. I have downloaded Zoom on my MacBook Pro (brand new last year) but for some reason when we are all talking together other people in the meeting can't hear me and I just break up. Other users of Mac can always hear everyone else but not me. Do I have to do something in my settings? Sorry if this is confusing but its difficult to explain. Basically when I talk it seems like my microphone turns off and then turns back on when its quiet and no-one else is talking. It works fine on my iPad though. Its sooooo frustrating. Thank you.