You want the audio to go out via HDMI versus the built-in speakers - do I understand correctly?
Have you looked at the Playback device and Recording device settings via the speaker icon located lower right screen corner? (Trusting that it has not been moved.)
Right click and select Playback devices. Find your device and check the configuration. Change (one on thing at a time) to see if you can control the audio as you would like to do.
Otherwise more information is necessary with respect to your setup and requirements.