Color of theme of Start10

When I try to configure Start10 (change settings), the windows/backgrounds are grey (background on left where a vertical column starts with Style and beneath that is Control, Desktop and About. On the right side of the window of which I speak, it is Black. I was sure that at one earlier point, the background was already light or I could change to enable light theme. As it is, I cannot tell what choices I am making. Hope this makes sense.  From: [email protected]