Going snowblind!!!

I know that this SHOULD be easy.  The design file background is white.  I have tried going to file>settings>preferences and choosing "black background -> White" both on and off with no change.  I have tried going to file>settings>Color Table and changing the B to a different color, but I get no change.  How the heck do I change the background color.  After 8 hrs straight of looking at a white screen, my eyes are killing me.