Editing Icons

Ok in some of the theme demos the icons have a few features that I cannot seem to find. From enlarging and filling with the accent color to disappearing when the mouse hovers over it – it seems as though these are features that connot be changed from the backend editor and they are in the demos. I am not sure if the front end editor has this option because of the issues that has with duplicating text…It is like the three headed creature in Hercules. You chop off a head and two more pop up lol. Likewise, you delete the unwanted text and more are there next time than you initially deleted. Anyway this is about the icons not the front end editor. Where can I edit this to make the icons have these features?