Musescore 3 Won't Play through Wired Headphones

I created a thread last night on this topic and then the problem seemed to be resolved - I thought.
I'm using MuseScore 3, Windows 10, I have wired headphones; just run of the mill, plugs into the phono jack headphones, which worked fine with MuseScore originally, plugged into the aux port. I bought a USB adapter to make it easier to connect to the computer, but then MuseScore didn't like that and I had to play around with the settings to get them to work again with MuseScore. Worked with EVERYTHING else, but would only work with MuseScore if I had it set so I had to manually switch the audio device in use in the Windows sound settings to get it to play in MuseScore, instead of switching automatically when plugged in.
Over the weekend I got a USB hub, for several reasons; among them to plug the headphone in through, since it has a power switch for each port. But when I plugged it in, MuseScore stopped outputting to the headphones under any circumstance. Whether plugged into the hub, plugged into the USB connection as the last time it was was working, or even in the AUX input on the front/top of the computer.
I tried every step I found in other support threads, I uninstalled and reinstalled the drivers for it, I followed the information in the FAQ, I tried every related combination in the I/O settings for audio output, but every time the headphones were enabled the playback controls were grayed out and it wouldn't even let me change anything in the I/O setting.

After I posted my earlier thread last night, I was taking another crack at figuring it out, and happened to see that my default sound device didn't have the headphones set to default - even though that was the last configuration I had it set to and hadn't changed anything. So I changed it back, and even though I had tried that setting before, all of a sudden it worked again in MuseScore. I could even turn off the hub port for the headphones and switch between speaker to headphones and back again, like you're supposed to, without even having to restart MuseScore. So I revised the earlier thread, that everything worked (because apparently you can't delete a thread...) and it worked all day today.

And now it stopped working again, and I have no idea why. The ONLY audio change I made was in the settings for VLC Player, changing the Stereo Mode to Headphones, because it was the only way to hear the dialog on a DVD I was watching through my speakers. Yet for some reason after that, even though nothing on the rest of the computer was changed, and there's no logical reason the settings in VLC player should effect the functionality or playback in MuseScore (and I even tried reverting those settings, to no avail); it's the only change in any kind of setting that even remotely corresponds to MuseScore failing to work with the headphones again.
It does not help that you have to restart MuseScore with each change of output setting to get MuseScore to accept the changes; especially since it won't show you any settings to change while the headphones are set as the output device, so you have to change it, change the settings, close MuseScore, change the ouput back and restart MuseScore; and then see if the controls are grayed out, and sometimes they aren't, but only because MuseScore changed the output settings you selected... And to add insult to injury, manual changing the output device can affect the default device settings Windows, further making it difficult to troubleshoot this stuff....

And MuseScore 4 is out of the question. There are far too many other issues with that program, that I've outlined in a separate thread, and don't outweigh this issue enough to switch for this one convenience.
I'd just like to know what in the world is going on, because I'm getting really frustrated with it working, then not working; and there is NO rhyme or reason.