audio stack incomplete in KDE plasma desktop system [SOLVED]

[mounty1]

Hello, I got audio working completely on my Intel NUC machine but after an update, it seems no longer to be so. Sound is supposed to happen via the HDMI connection to the speakers built in to my monitor.

• Skype sound works, through the speakers on my monitor.
  
• GVIM pings when it pops up a dialog, through the speakers on my monitor.
  
• System Settings -> Audio and Video -> Audio Hardware Setup -> Front Left / Front Right buttons do produce the front left and front right spoken phrases but swapped left to right which is odd because it's an HDMI connection and I can't find any channel swap control.
  
• System Settings -> Audio and Video -> Device Preference -> Test produces a dialog Failed to set the selected audio output device and no sound. The selected device is Built-in Audio Digital Stereo (HDMI)
  
• Youtube sound (browser: qupzilla) no longer works.

So there's something missing in the sound stack. Any suggestions?
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Michael Mounteney

[mounty1]

With Qupzilla playing some sound, such as on Youtube, bring up Audio Volume Settings, click the Audio Volume icon, then against Chromium playback, click the drop-down list button and choose HDMI output. On my system, it was set to built in audio analog stereo.
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Michael Mounteney