is there a way to change the appearance of ring dropdown menu (see attached image)?
There is no dropdown menu visible under control customization.
Unfortunatelly there is no possiblity to change the appearance of ring dropdown menu.
But you can post your suggestion here and our R&D will take a look at your proposal:
You can see near your post how many kudos you got from other users - more the kudos you have more probable is that your feature will be in the next edition of LabVIEW