This is a problem since years.
If I switch my sound device on Windows 10, everything except Minecraft switches the sound. For example: I'm playing through my speaker and I want to switch to my headset, I select it as my sound device. Spotify, Youtube, other games etc. everything switches to my headset. But Minecraft don't want to switch. The only way to solve this, is reloading all resources with F3 + T or reselecting a Resourcepack, or with restarting Minecraft after I switched the device. But it takes like 2 Minutes for me to load everything, because my Laptop is very slow. Two Minutes or more, just to switch the Sound to another device.
How to reproduce
1. Enter a World (should also work with the title screen music)
2. Put a Disc in a Musicbox, so you have loud sound do demonstrate that (you can use everything else to produce sound)
3. Switch your sound device (maybe from Laptop speakers to a bluetooth headset)
4. You can hear, that Minecraft won't switch the sound device
5. Press F3 + T
6. Wait a bit
7. you can hear, that the sound is switched