The question is regulary asked here; "Should I use the 40 degree or 30 degree setting to sharpen s on my Sharpmaker?" The short answer: use the 40.
The primary bevels on s are ground to around 30 degrees at the factory (They will sometimes vary, because it is done by hand).
"Sharpening" generally means adding (or restoring) secondary microbevels, at a greater angle than the primary bevels. Hence the 40 degree setting for sharpening.
The 30 degree setting is there for reprofiling (resetting the angles of the primary bevels). If you want to sharpen (add microbevels) using the 30 degree setting, the primary bevels must be well below 30 degrees.