Gray background changes to white, will not change back.

The Brig

Somehow in mid-project the gray background in DS 4.9 (on Windows 10) changed to white.  I don't know what caused it as I was just changing my views from one side to another.  Now I'm unable to change it back.  I've gone to the Environment tab to try changing the color back to gray, but then I lose the grid lines and when I change my view, the background changes back to white as I move then goes back to gray without grid lines.

The Environment tab is set to Type: None just like it was before this happened.  What could the problem be this time and how do I get the original settings back without reinstalling everything?

Szark

In DS go to Window > Style > Customize Style > Viewports once you reset things Save the Style and Workspace.