To change your application icons you will first have to look up an image you want to replace it with (it is the easiest if the picture you get is in a .png file format.) Second open finder, then applications, and then click once on the application you want to change. Then press the command and i keys at the same time. Then open your image you just downloaded in preview, then press the command and a keys at the same time, then press the command and c keys at the same time. Then go back to the get info window that you just opened and click on the application icon in the top left, then press the command and v keys at the same time. Type in you password and your application icon is changed. Follow the video above watch me to change my icon, and follow it again with the real application icon if you want to change it back. You can always press command z to undo the application change, but this only works right after you change it.