Hi Julia,

Your drawing was created from the template with named plot style table (STB based). Named plot styles can be assigned to an object independent of color.
But you are talking about drawing based on color-dependent plot style table (CTB based).

In AutoCAD for Windows you can use special command to convert plot styles, but on Mac the only one way to convert drawing from named plot style table to color-dependent plot style table:
Create new drawing using one of templates with color-dependent plot style table - acad.ctb (for Imperial units) or acadiso.ctb (for metric units), then select everything in your drawing and copy - paste to newly created drawing.