See if this helps:
If the v-carve is going to be cut with a single pass, then the Stepover values are not used.
If the v-carve is too deep and wide to be cut in a single pass, the depth for each pass is controlled by the Pass Depth you have set for the v-bit and the "Clearance Pass Stepover" controls how much horizontal movement takes place as the v-bit 'clears' the center material for that pass. This can be as coarse as your machine/bit/setup allows as it is just roughing out material which will all be removed when the toolpath completes.
If you have the Flat Depth option checked, the "Final Pass Stepover" controls how 'smooth' the flat bottom will be. The smaller the stepover, the smoother it will be however with a true v-bit (comes to a point) you will always see ridges. Also, the smaller the stepover, the longer the machining time. If you are using the Flat Depth option, it is always best to use an endmill to clear the flat areas and then the v-bit will only need to clear any flat areas where the endmill could not reach.
You can easily see the effects of different settings by calculating the toolpath, preview it and inspect the blue lines. These lines are where the very point of the v-bit will be traveling.