Click on the COLORS button near the center on the left of the window. A new dialog box will come up. At the TOP on the LEFT, there will be a box called Content. Select (it will highlight when you select it) the 2D MODEL SPACE option. Then near the center of the window, on the interface element OPTIONS, select the UNIFORM BACKGORUND option. Then, on the top right of the screen, there will be a COLOR option box. Click on the arrow to bring up a list of colors. Pick the one you want (I chose black).
That is how you switch your colors, for anything. Play with the options and see if you can come up with a better color solution.Happy CADDING