Welcome to the forums!
In the past there seem to be more customers reporting that they couldn't get audio through HDMI , so seems a little ironic you want the opposite thing 🙂 .
Thanks a bundle for responding. But No, I do want the sound, but I need to be able to control the volume (especially the mute/unmute function) without interfering with video playback or PPT with video and sound. It is the loss of keyboard controls for the sound via HDMI output that has everyone puzzled here.