I'm lecturing with Zoom and Impress (Libreoffice) on Ubuntu 18.04.
The Ubuntu (really Gnome) Sound/Applications panel has two ZOOM VoiceEngine sliders. The top one controls what I hear from the remote side. The bottom microphone slider is no problem it just stays where I set it. The top one goes back to zero from time to time, seemingly when I switch windows.
How can I lock the top one down?
I did notice one pattern on my workstation. When a student adds or leaves the zoom the slider goes to zero. There may be other triggers but that one is consistent.
However, in another new experiment I tried running zoom on the Ubuntu workstation against Zoom on a Ubuntu laptop. When the host is on the workstation, the bad behavior shows. When the workstation is the client and the host is on the laptop no bad behavior. Same version of zoom.
I don't know what could be different on the workstation to cause the problem.