does the USB device appear in the list of audio devices?
No idea why the uninstaller doesn't remove the virtual audio device but it's probably still set as a default device.
you can change it using the new settings menu:
https://winaero.com/change-default-audio-device-windows-10/
or,
if you are a bit old school you can use the old Windows 7-style menu instead:
https://www.tenforums.com/tutorials/102323-change-default-audio-playback-device-windows-10-a.html
The old method gets hidden/moved/removed by Microsoft but it won't go suddenly away.
https://cloudconvert.com/mp3-converter
This may sound weird but this fixes it for me. Convert the mp3 file to an mp3 file. Trust me it sounds weird but it fixes it.