Problems with Audio on Zoom

I have had problems with Zoom Audio ever since I changed to a  Lenovo PC 3 months ago.

I test my audio settings beforehand and the microphone works perfectly ok for recording and playback. When others join the meeting we can all talk together.

We then have a bell ringing group where we all play 2 bells using a separate program. This works ok until I say "BOB" which the others can't hear even though I am saying it very loudly, as my wife will testify.

I have tried three sets of headphones with mic and even the computer mic and the same problem persists. 

I have tried adjusting various audio settings but to no avail.

Any thoughts please ?