I've entered some color changes by clicking on the Customize Button for the Plain Yogurt Theme. Then I saved the changes.

In the preview of the Plain Yogurt theme my changes show as they should.

The changes I made do not show up on the site.

I selected another theme and then reactivated the Plain Yogurt Theme. I get the same result, the changes are reflected in the Admin back end but not on the site.

Is there something else I need to do?

I've attached an image from the preview and from the actual - note the color of the text,"Concept Test Site..."