It keeps auto changing default soundcard output source

I have soundcard built in to motherboard, i do not use this, it is set to off. i also have a Creative Soundblaster PCI soundcard, but i currently have no speakers so it is also set to off.

So, I have 3 monitors, 2 DisplayPort connected, and the 3rd HDMI connected. in the osund settings i have HDMI 3, HDMI 4 and HDMI 6 and ONLY HDMI 6 which is connected to the ultra-widescreen monitor via DisplayPort is the one and only monitor i have that has speakers and this is the source i want to use. BUT whenever i turn off monitors during the night, leave the computer to sit by itself for prolonged hours or some game changes the resolution my sound ALWAYS defults back to HDMI 3… this is bothering me. i cant turn off HDMI 3 and 4, the 3 of them are lumped in the same profile.

i also installed Pulse Volume Control and i cant turn off HDMI 3 and 4 there either.

pls help.

Welcome to Manjaro Forum

Use this command to show the audio playback devices on your system and find the card number for the HDMI outputs

aplay -l

Then use the card number to open ALSA controls for the audio hardware
if the card number is 0 from the previous command:

alsamixer --card=0

you should see the HDMI outputs like this:

Use arrow keys to select each HDMI output
and M to turn off all the outputs [MM] leaving only the one output wanted showing as on [OO]

After closing alsamixer save ALSA settings so HDMI outputs remain muted when system is restarted

sudo alsactl store