Referenced cells do not identify themselves with color

For some reason when I create a formula that references other cells, I cannot get those cells to "identify" themselves with a specific color. For example, in the image below the formula references cells B7, B8, B6, etc but they are just black text and don't show up in color per standard excel documents. Usually they "glow" with a specific color so you can find them easily in big spreadsheets. How do I get the colors back?