Strange music volume behavior for the PC audio shareing

[TakaZZ]

This phenomenon happens only one PC, though I have multiple PCs. (Windows11 HP Note PC with AMD Ryzen5 7530U) I’m a dance instructor and use Zoom for my class. The issue is the delivered music volume level for student side. I’m using “Share the Computer Audio” function and the volume setting on my PC is 100% (max.) both for build-in speaker and external speaker.

<<Until Zoom Ver.5.15.5>>

1. When I use the build-in speaker, delivered sound volume is low.
2. When I use the external speaker, delivered sound volume is fine.
3. Once, I use the external speaker, even if I back to build-in speaker, the delivered volume is fine. Never back to #1 situation.
4. The volume indicator (free app) shows no difference between #1 and #3 volume on my PC. Nevertheless, delivered music volume at the student side vary.
5. When I delete the build-in speaker on the device manager and re-boot the PC, the device driver will be automatically re-installed. Then, the situation back to #1, low volume level.

<<After Zoom Ver.5.15.7>>

1. When I use the build-in speaker, delivered sound volume is low.
2. When I use the external speaker, delivered sound volume is also low.
3. When I keep connect the external speaker but set the build-in speaker as “Default device” on the sound control panel, then the delivered volume is fine.
4. When I disconnect the external speaker, the delivered music volume become low again.
5. The volume indicator (free app) shows no difference between #1, #3 and #4 volume on my PC. Nevertheless, delivered music volume at the student side vary.

Until now on, I thought the cause will be PC hardware, device driver, or Windows. However, I found the behavior vary by Zoom version so now I doubt Zoom app itself.