I searched for the awnser a little and found this: https://itectec.com/ubuntu/ubuntu-how-do-you-set-a-default-audio-output-device-in-ubuntu-18-04/
Gonna save this here, because I am going to search it one day again.
- Run:
pactl list short sinks - Note the device name you want to use as default
- Try to run:
pactl set-default-sink <Your_Device_Name>
This should work without giving you an error message. - Open the application “Startup Applications” (Should be preinstalled on Ubuntu)
- Click on “Add”
- Give your startup item a name
- Copy your command from above into the command field:
pactl set-default-sink 'Your-Device-Name' - Click on “Save”.