I think we may need a screen shot for the mentioned artwork.
However, after you choose the needed color for the (stroke) and the (Fill) of your object, you can also transfer the (Strokes) to (Fill) or object, by selecting the outline then go to Object> Path> Outline Stroke. you will have it now as object and you can add a stroke color for your lines.
For the purpose of seeing white bits, you may create a (temporary) object behind the artwork or use Simulate Colored Paper in the File>Document Setup, either with a suitable (fill) colour.
Have tried various things but cannot get it to work??
Are you sure that all those areas are different objects?
You will need to show the artwork.
We will also need to see what's inside your layers.
An outline view might also be needed to see.