Home tab > Layers group > 
Layer dialog menu > Color by objects, DISPCOLORS
Home tab > Layers group > Layer dialog menu > Color by layers, DISPCOLORS
Set the program to display colors either by individual object colors or by the color of the layer that the objects are on.
Every object has its individual color. However, you can set all objects on the same layer to be displayed in the same color defined for that particular layer. The command does not affect the color information of the individual objects, only the way the program displays them.
Since the display color of objects determines their line width in printing, you can print all objects on the same layer with the same line width by changing the layer colors.
You can check the color of each layer by selecting Tools > Layer.