usb recording is only one channel

new windows 7 pro fresh install but I've had this problem for years with windows 7 , 10 , 11 and so on. I'm just trying to record laserdisc to my hard drive . So I have my player into a kramer vp773 and run hdmi out of that to a hdmi to usb adapter and into computer. If I run the hdmi out to my tv everything is fine, running a test disc for 2 channels where it states "left channel and plays a tone and then right channel and plays a tone all is good. I get left channel only and then right channel only, so that works fine. However when I plug the hdmi into the adapter and into the computer I only get the left channel on both left and right side .When I go into properties for the "usb recording device" the only recording option is 1 channel. so I see no way to get 2 channel stereo. So in amarectv that I use to record the laserdisc I select no audio and I just run the 2 channel right / left audio from my laserdisc to the line in of my computer but when I do that and run the right / left test it begins to play left side and immediately begins to play it on the right side also, and when it plays the right side it also begins to play that on the left side along with playing it on the right side. It's like windows senses silence on the channel and fills it with audio from the other channel. I suspect this happens to alot of people and they don't even realize it. It used to happen when I would use usb cature devices also and I tried probably 10 different ones and this basicly happened with any windows computer except I think it worked properly in windows xp, so I don't think it's anything with any of my setups , I think it's something to do with the windows system regardless of what windows system I'm using. So what I ended up doing was recording audio with a small digital recorder and recording video on the computer and then I "mux" them together and that works and I've done alot of discs and video tapes that way, but I've always have wondered how to just record video and seperate right / left audio onto the computer? I'm open for suggestions, but as I said from the start , if I just plug my hdmi to the tv all is good I get left side tone only in left side and right side tone only in right side so that works properly, but pulling the hdmi cable out of the tv and into the computer , it always feeds right side into the left side and vice versa and it's always done that on all my computers whether it's 7, 8 , 10 or 11. It seems to be set up that way in the firmware or whatever, and as I also said, many people may have the same problem and not even realize it. When I google the problem there are about 100,000 people with the same problem but for about 10 years or so I have never seen a solution. Thanks for the help in advance.

See if this helps

*FIX* Capture Card Audio | Mono to Stereo Audio TUTORIAL
https://youtu.be/n-JWzTau-Hw?si=HatiMu3CvUl2zZjo

yes , that's exactly my problem but all of that was waaaayyyy beyond my comprehension level, totally lost . There has to be some easy fix for it, I just don't know what it is.

I had a similar problem when I was digitizing my library of audio LPs. I used a Behringer UFO202 USB device to capture the turntable output into Audacity.

I discovered the Windows default is to record in mono with only the left channel on both Audacity stereo tracks. From what I gathered, this is not a problem specific to the Behringer nor with Audacity, but with the way Windows defaults new audio recording devices.

My solution was to plug in the Behringer, then go into Windows’ Sound Recording Devices settings and change the default from mono to 2-track stereo.

yes when I'm trying to input thru usb that's exactly what I want to do but the option to change to 2 channel isn't there. The box states 1 channel and it's greyed out so I can't select 2 channel. When I input into the line in it is recording right and left but after about half of a second it feeds the sound into the other speaker also, and yes I do think it's something to do with windows. I did notice I have another audio control called dts that's a brand name I guess from intel maybe , it's not something I installed but I have that disabled but I'm wondering if that has something to do with it, I'm thinking of seeing if I can uninstall it, but I have had this problem with pretty much all windows computers. For my lp's I also recorded them on my little zoom digital recorder, which I liked better anyway because I would get a little bit of hum / noise recording with my computer.