I have 2 different lines with symbols on a graph. One line represents the target value and the other line represents the actual value. I want the symbol on the actual value line to be red when above the target value and blue when below the target value. I understand that I can change colors based on whether the actual value is above or below a manually entered value, but the target value changes every month, and I need the color of the actual value to automatically change when it dips below or rises above the dynamic target value.