Can hear clear 'voice', but cannot hear clear 'other sounds', because of some sound setting

Hello, I am a laptop (dell) user.

I cannot hear the presenter's voice CLEARLY, also the voice from the sharing video.

But I cannot hear the OTHER SOUNDS like the presenter's piano playing sound, and BGM in the sharing video.

What makes it a "software bug" is,

1. Of the many listeners, I was the ONLY PERSON who experience this problem (they said they could hear the BGM or instrumental sound normally).

2. I COULD hear the BGM/instrumental sound well, only a few seconds when I changed the "microphone selection" or "speaker selection" option during the meeting. (So, to hear the BGM well, I should change the 'speaker selection' option every 5 seconds, from 'same as the system' to the embedded speaker, and from embedded speaker to 'same as the system).

3. This 'temporal normal-sound state' comes when the other app's (e.g. messenger app's) notice rings.

4. I can experience the same symptom when I try "speaker & microphone test".

I am really suffering from this error, so please give me some advice, and I'll really appreciate to it.

Thank you.