PAN /Stereo

Hi,
1. I have a new computer - a desk top. I have downloaded MuseScore 3.6.2 which is the same as I have on
my old lap top. On the LT the PAN / stereo system works fine. Instruments that I put on the left come out on the left speaker. Likewiwse for the RHS.
Now on the desk top no matter where I place the insturments, full left or right they still sound in the middle when played back - no panning. Is there some setting?

2. Menu background colour. For some reason the text in all the menus has gone white and the background black. How do I change it back to what it was?