Thanks to all who posted about this, especially for the accepted solution(s). Since folks were still posting long after that solution was posted, I thought I would try to add an explanation, what worked for me. Like so many others I could not get sound out or mic in to work using the ring app on my Windows 10 laptop.
Those default windows settings can be tricky - it seems that every app accesses communications services differently. Even ring works differently for live view than it does, for example, when you play various choices for notification sounds in the app. For sound output on the PC I had three output choices and my laptop speakers and the output jack worked fine for things like media player, zoom, youtube, etc, - even in the ring app it worked for playing sample notification sounds - but not for ring live view. So, in control panel I changed the “default communications device” to the speakers/jack and still no help. For grins. I rebooted and then sound worked - ie with those new settings and after reboot!! Now I had sound sourced at my ring pro doorbell and coming through clearly on my PC laptop speakers and the aux jack, while in Live View in the ring app on windows 10.
Then I found that the laptop’s mic was not transmitting the other direction while in live view on the ring app on windows 10 - even though the mic worked fine for zoom. For grins I also tested the mic with the included windows 10 audio sound recorder and it did not work either. For some reason I had TWO mic choices in control panel, so I changed to the other one and disabled the one that was formerly active. At that time I also set the sensitivity to maximum (somewhere in that area, under properties or settings of the mic of choice in control panel). Windows sound recorder started working! But mic in ring app did not work yet, and finally I exited the app and restarted the ring app and now EVERYTHING works. Well, I still need to re-test zoom and some other functions. It’s possible I never had to reboot for the sound output, I may have only needed to exit the ring app and restart it. Hope this helps someone.