You can't alter the depth of the finishing toolpath, it is a single pass at the surface of the model. You can alter the position of the model within the material block as highpockets has said.
It may be that you have the model sitting to deep in the material block which you can change in the material set up on the toolpath side of the screen. what does the toolpath priew look like ??
Screenshots or the actual file (copyright permitting) would be a help in solving your problem