Sending Minecraft audio to different output device?

Minecraft doesn't support outputting audio via a specific audio device. With the diversity of the actions whose audio you want to send to your TV you're probably going to experience issues making it work as you want to.

For watching movies or TV shows that exist as data on your PC, you could swap the media player you're using to one that supports outputting audio to a specific device rather than the Windows default device.

This would mean setting your PC's audio device as the windows default device so that Minecraft uses it, and then manually setting your media player to use the other audio device.

VLC supports outputting to a specific device using the "DirectX Output" audio module, available under audio in preferences. This would allow you to play media files and output audio to your TV while running Minecraft outputting audio over the default sound device.

This won't work for YouTube however, and web browsers, like Minecraft, do not have the option to output to a specific audio device, so there wouldn't be a workaround for this.

Load/Change a Resource Pack in-game and for some reason, it causes Minecraft to switch to the default audio output!

Let me know If it works for you.

if your using an HP computer then go into the sound settings and scroll down and below the troubleshoot option you will see "App volume and device preferences", click there and you should be able to choose what apps use what output and input devices.

i had a similar issue where my Minecraft audio would play through my computer speakers and everything else played through my Beats so I had to change it so everything plays through my beats

The fastest and easiest way to deal with this (until Mojang gets around to fixing the bug, assuming they ever do), is to simply press F3+T. It doesn't require quitting Minecraft or even rooting through the menus (though it will still take a few moments to reload the assets).