Color Temp Confusion

Color temperature is simple, yet it continues to puzzle me. Help. Do I set it to 5000 degrees or something else? My light table is 5000 degrees. Aperture defaults to 5000. So, why does my printer say 5000 degrees is old school from days of CRT monitors. He says prints need different color temp from on-line stuff. NTSC color TV defaults to 6500 degrees.