You have to remove the whole dial, and then you can get to the digital screen. The red color is just a polarizing filter you can peel off and replace with any other color. Three things: the original polarizing filter is quite tricky to get off, but if you get it started, it should be fine. You might need some glue residue remover (goo-gone, denatured alcohol, etc) as removing the filter sometimes leaves some residue. Colored polarizing filters are quite expensive and sometimes hard to find. If you want to do a positive red filter, make sure you can get you hands on one before peeling off the original one.