The next option in the Modify group is Layer Start.
This is used for changing the starting position of each printed layer. It is possible to choose to set a point or a line for doing so. When drawing a point, the layer will start at the nearest point on the solid surface.

It is also possible to move and orient the Grid depending on the necessities when drawing the line or the point for the Layer Start. 

By clicking the Grid button a list of options will be displayed, used to relocate the Grid on the various surfaces of the solid and to modify the Grid elevation.