On some bows it makes little difference where they cross, on others it does. Most bowtech bows have them cross below, even though at the brace position if you remove the slide, they want to cross above. The reason they cross them below is because the draw cycle affect where they want to naturally be. On Max-cam bows (Mathews) and similar 1-cams, they typically cross above. On Mathews straightline style cams, they typically cross below.

The cable should be in the longer groove and the string in the shorter groove regardless of where they cross.

As a check you can take the guard off and see where they want to cross, then draw the bow without the slide and see if the location of the cross dramatically changes and make a determination where the cross should be forced to be when you install the slide.