U4924DW, DDM windows size options

I recently purchased a U4924DW 49 inch monitor and it is awesome. Using Dell Display, there are many window set up options. I am using the four window option with the left being over under and the two to the right being normal size. I don't need a lot of real estate for the over under windows to the left. Can the window options in easy arranged be resized to make some small and some larger? Is there a way to permanently resize them. The yellow size lines will appear on the scene but I cant seem to adjust them.