In the Icon Shape drop-down menu [1], you can select the shape type you would like the icon to be. You can select between square, circle, triangle, diamond, pentagon, hexagon, octagon, and star shapes.
If you would like to modify the size of your icon, use the Icon Size drop-down menu [2].
To change the color of your icon, click the Icon Color drop-down menu [3].
To edit an outline to the icon, click the Icon Outline drop-down menu [4].
If you would like to modify the size of your outline, use the Icon Outline Size drop-down menu [5].