Mac Mini M2 can barely hear Zoom

As Mac Mini has no speakers, I am using a basic set of Logitech speakers (plugged into the mini with a 35mm jack) which is fine for listening to video, music, et cetera. But when I use Zoom (with an external camera), the audio does not come out of the speakers. It comes out of the mac mini itself, and the volume can be neither turned up nor down. Others on the Zoom have no problem hearing me through the mic in my camera, but I can barely hear the discussion. How can I get the call audio to come out of my external speakers?