Audio Problems

Hi Guys
I have a Asus Vivobook 15 with Windows 10. My problem is that when I use zoom the sound output is always quiet. I have tried adjusting the volume in Zoom and with the Volume Mixer. I have a JBL soundbar plugged into the headphone jack and have also tried headphones, same result. This doesn't happen with other applications. It's driving me crazy as I try to have work zooms and can't hear the other participants.
I tried uninstalling and reinstalling Zoom but no change.

When I test the different output options it seems to vary as to which one works and if I go back to one that works often it won't. I know that sounds a bit foggy but the whole thing is fogging my mind!
Any ideas would be gratefully received
Terry