The default color of ByLayer Color is white. Can it be changed to black? In AutoCAD, ByLayer Color is black if the graphics background is white.

I realy don't understand what the question is. "By Layer" is not a color. It is a setting which enables the layer to control the color. Yes, when you create a new layer, the default color is white. If you change your screen to white, the white lines will show black.

In the Options/Display dialog box, I changed the "Graphics Screen Color" to white (RGB 255) and I couldn't find "ByLayer Color" on that dialog box. This afternoon, I changed the "Graphics Screen Color" to white (AutoCAD Color 7) and "ByLayer Color" is automatically changed to black. Why isn't this in the manual? Why doesn't IntelliCAD import and export 3DS files? I could use DXF import and export but 3D modelers usually don't support ACIS 3D solids.

May well be that you are not using white. Change color of screen and lines to 7.