Mark, don’t measure, in order to produce parts that are the perfect size. Starting with a side piece, lay the molding against the cabinet and draw a line on the molding to mark the position of the front corner.
Position the molding against the fence with your pencil mark aligned with the line-of-cut indicator you cut into the fence. Make the cut.
Confirm that your first miter is a good fit, and then continue to work your way around the cabinet trim, marking out and cutting the remaining pieces.
Position the pieces on the cabinet. Use a clamp to hold the parts until you have nailed them in place. Use a brad nailer to fasten the trim. Be sure to shoot the brads through the molding and into the plywood case, not into the solid top.