I have had my MacBook for a couple of months now, and the minimize and maximize buttons are all grey. They weren't like that when I got it. Does anyone know how to get the colors back?
In System Preferences, there is a setting for overall "Appearance." It would appear that your appearance has been set to "Graphite" instead of the default "blue." While the maximize and minimize buttons are not blue, when the appearance is set to blue, they are in color; when the appearance is set to graphite, they are grey.