I have checked the forum and seems that this is a quite common issue with Acer.
My monitor is a new EB321HQU Cbidpx, and has the 3.5mm audio port a DP port and the HDMI. My nVIDIA RTX 2060 control panel does not see the audio for the monitor.

I have forced the install of the Win8 64 bit drivers as there were none for Win10, and still can not get sound to the monitor. The monitor is in the OS's the volume controls.
The device manager in Win 10 see's the monitor as Acer EB321HQU, the sound settings ID the output channel as EB321HQU C (NVIDIA High Definition Audio) correctly.
Any suggestions??
Thanks!