You can add a designer-quality look and polish to your shapes by applying a Quick Style (Quick Styles: Collections of formatting options that make formatting your documents and objects easier.) to all of the shapes in a page.
If you apply a Quick Style to a shape, when you change the theme, colors you can change the professional designer-quality look quickly.
Under Page Layout tab, in the Themes group, change the Theme, Colors, Fonts or Effects.
In the Quick Style list, right-click the item and choose the Set as Default Style item.
Then all the new added shapes will apply the style automatically.