1. Click "See inside" 2. Go to the sprite named "ICON" 3. Click on the "costumes" tab 4. Replace the template with whatever you want! (Mine is an angry face.) :)
I suggest you do full screen. If you set the Icon to show, you have to do turbo mode (shift+green flag) or else it'll be slow. If it is on hide icon, If you do turbo mode, It will be fast.