Although the color scheme for your document is set automatically when you choose a theme and a variant, you can select a different coordinated color scheme if you like. Word includes a number of palettes with complementary colors already assembled for you.
On the File tab, in the Document Formatting group, click the Colors arrow.
A palette of color schemes appears.
Scroll through the list to find the color scheme you like.
Click the color scheme you want to apply.
You can also create your own custom color scheme. At the bottom of the Colors list, click Customize Colors ...