When ADX is low, EMA color is in lime or aqua, if the value of ADX moves higher, It changes from aqua to yellow and then red. You can change the settings like EMA period and the color, etc in the dialog window.
Usually, as the trend becomes stronger, the ADX values rises, so there is a possibility on a trend when it is yellow or red. Especially, when changing from aqua to yellow and red, it is a necessity check because it is a possibility of change from range to trend.