I'm using Ubuntu with Rise Vision for digital signage at our company.
Its hooked up to a HDMI display with audio coming through the display.
Its been working great until the end of summer after some updates to Ubuntu.
Now everytime I reboot (Which it does every evening) it changes the default Audio Device to the one in the computer instead of the HDMI. It has never done this before.
I've tried to disable the onboard audio device, but it doesn't help. It keeps selecting it on startup.
I've even tried to stop it from rebooting, yet every morning it seems the audio device has changed.
Best Answer
You can use pavucontrol (pulseaudio volume control, install if necessary). Launch it from multimedia menu, go to the "output devices" tab, and click the green "define as alternative" button that is near HDMI soundcard.
If it still doesn't work, look also "configuration" tab and change profile.