Obs taking microphone as speaker

[Carrot]

Hi
I use USB Headset (Fantech HG11). I don't understand the audio settings properly. in playback devices, if i choose the profile 'analog/digital stereo + mono input' I can use my mic and headphone. but if I choose 'mono input' or 'analog/digital output' I can use it only as a mic or a headphone. (Explain this)
so i chose digital stereo output + mono input. I can hear everything clear, other can hear me clear. That;s alright.
But while i use OBS for recording or streaming, desktop output does not take any computer sound, it takes my mic.

1. mic muted physically : no voice + no desktop audio
2. desktop audio + mic both enabled : hear me twice
3. desktop audio enable, mic disable : hear me like as if I am in some network issue
4. desktop audio disable, mic enable: hear me

youtube: 2021 11 19 10 11 05 - YouTube
inxi -faz thing: Carrot inxi -faz

edit: typo

[Carrot]

hello world

[Carrot]

detailed thread : click here

well those wireplumber didn't work for me, i switched to pulseaudio. everything is just fine.