Unable to change default volume level in Zoom room.

Hi there, 

We have a few Windows Zoom rooms. The default volume level of these units seems to be 100%. If I lower the volume in a call and hang up, the unit will start the next call with volume at 100%. I didn't find any place in the portal to change this. I tried changing the volume level in Windows but it still went back to 100%. Any ideas for how to change the default?

Thank you.