New computer and now bad stereo recording

[roadsterUK]

Thanks for your post. I am using Win 10 and Audacity 2.3.3 as well. Bloody Windows really hid the setup well.
In my setup screens it goes like this, which is very similar: Windows Settings; System; Sound, then find the (grayed out) Sound Control Panel (upper right); Recording tab; select Microphone, then Properties; select Advanced tab - finally to discover the Default Format setting. Which of course is set to 1 channel !!!!!!!!! as the default.
Changed to 2 channel, matched the sampling rate of the A/D box (Pro-Ject AD Box S2 Phono), and now I have both channels.
I had just set everything up and started recording my old albums since I was now working from home, so I was not closely monitoring and did not notice the error until after 33 albums. When I did notice I thought it was the A/D box and got a replacement (thanks Crutchfield). Tested it yesterday, and of course it was just the same. Which is why I am here.
The Forum (especially this post) saved me hours of frustration. THANK YOU for leading me down the path to get this resolved!
Stay Safe and happy recording!

For future reference the simple way to open the sound control panel is to use the run command and type in
mmsys.cpl
You can also type this into a command prompt window.