Check the volume mixer (Right click on tray speaker and select "Volume Mixer".) to ensure the main volume is where you want it and that the volume level for your browser is also at a desired level. (I'm using YouTube in Chrome. MS Edge's volume is the same as the main system volume.)
Next check the volume level on the YouTube video iteslf.
Hope this helps and I wish I had something more for ya.
I am an HP Employee Quality Manager - HP VR / Z Desktops ----- “iMaxx” FORMER VOODOO PC / HP LEGACY GAMING SERVICE MANAGER While I am an HP employee, my comments and suggestions are my own and do not represent HP Inc.