Sound Works But Output Randomly Changes

I have a Toshiba laptop about 6 years old running Win10. I was using headphones plugged into the phone jack and then about a year ago I got a dongle dac and plugged it into a USB port. No problem. Then a few months ago, I bought a USB headphone amp, plugged it in to the USB and no problem at all. Sound much improved.
Last Dec I got Qobuz, which I came use on a streamer or just on an app on this laptop without going to the streamer.
Then, last week, after listening through the headphone amp all morning, I came back and tried to listen to some music on the Qobuz app. It only worked on the laptop speakers, USB wasn't even a choice. I switched the USB port, went back to the USB dongle, restarted the computer, uploaded and installed the latest win10 update. Nothing worked. I went online to look or hinds but nothing worked. Then it started working again. Yesterday, the same thing happened. I went the sound card setting, ran the trouble shoot, looked at sound output and saw 2 different speakers this time on the playback tab. I shut the one down and it started working. Note: I didn't go change any setting and Qobuz has no setting options and each time the computer has been left on.
Today the same thing happened. I was on YT for a while listening via my headphone amp on the USB. Came back and went to Qobuz program and it would only come out of the laptop speakers. I just now unplugged to USB and replugged it and now the headphone amp is recognized and works. This is a very intermittent problem. Sometimes I can unplug and replug the headphone amp in and out of the same plug or use different plug and it doesn't work. Other times I can go several days and it all works seamlessly just like it has done for the first few months of this setup.
Any ideas on where the problem may be?