Chris P. answered 06/11/19
Experienced Teacher & Graphics Pro Keeps it Clear & Concise
Yes, artboards are white and can’t be changed. But there’s an easy workaround: create a rectangle of the same size, and fill it however you like. Then, either:
Object—> Arrange—> Send to Back, and lock it (Object—> Lock Selection).
or
put it in a new Layer, keep the layer locked & drag to bottom of the stack of Layers.
These large rectangles will visually function as colorful artboards.