In this step, we assign a PCB material to the two printed circuit boards.
1. Select the two PCBs by left clicking on both:
2. Click Edit from the Materials context panel:
3. On the Materials quick edit dialog, select the material type:
4. From the Name menu, select PCB 12-Layer(Y).
5. Click Apply.
What it should look like...
6. To verify that the PCB material is properly assigned, check the Design Study Bar and the part coloring: