JOSM and .kml polyline colour editing

I have found the presence of Public Rights of Way .kml files in JOSM to be very useful for comparative purposes. One drawback is that they appear as grey polylines. I cannot see a facility to change colour, and wonder if anyone knows differently? A colour key is present with a hexadecimal value as an attribute, but changing that has no effect.
NOTE: I have changed the colour codes in Notepad to no effect.