App (irium webcam ) changes default audio settings every startup

try with another way:

paste this in a file with a ".sh" extension inside /home/

#!/bin/bash
pactl set-default-sink **Your-Device-Name**

give the execution auth

chmod u+x /home/<yoursession>/<fileyoucreated>.sh

and fill the path textbox with these file location in the autostart config.

Remember deactivate this option when you want to not use those device anymore.