It's under the Display tab in Options. To bring up Options, right click on the command line and select Options, or click the red A and Options is at the bottom; then go to the Display tab and select Colors.
I tried that, and the only thing that changes is in the sheet view area, if i change the uniform background to black the sheet area goes black, but the rest stays grey.
That is correct if the only color you changed was for Sheet/Layout. You have to select your color change for each item in the Context row (2d model space; 3d perspective, etc.).
