Question: dpx500bt how to change color?
Answer: Press and hold the [AUDIO] button. Enter the Function setting mode.
Use the [Control knob] to select "SETTINGS" > "DISP & KEY" > "COLOR SELECT". ... 
Use the [Control knob] to select a illumination part. ... 
Use the [Control knob] to select a color ("VARIABLE SCAN"/ "COLOR01" — "COLOR24").