SE options - View tab - Arc Smoothness
and on the menu View Tab - Sharpness
The question is WHY do you want to change it:
1. You work on really big parts (10M across) and the arcs look too faceted?
2. You work on stylized parts and you want the highlights to look more clear?
The answers are different, depending on what you are trying to do...
You can change the way arcs look on the View section of the Solid Edge options. There are two settings... An Automatic-sharpen command that is off by default which I believe is dynamic and the Arc smoothness command which I believe is static. I believe the automatic-sharpen option overrides the Arc smoothness option.