All throughout the various products, check boxes look a different way.  Some are white and empty and some have a pre-entered, faint outline of a gray image of a check.  When you are ready to check a box, sometimes the white area then shows a black checkmark and sometimes the pre-entered faint, gray image of a check turns blue.  It just needs to be consistent.  I think most people these days know to click a check box when they want to select something and don't need the gray, pre-entered "reminder" to prompt them to do so.