I want to help, but don't exactly know what you mean. Could you maybe post a sceenshot with the filters in question?
Here a screenshot. With the Class 66 DBS you see the icon that looks like a brush, I do not know what that means.
I means you can change the livery. It tells you the key to do so in the bottom right when you select the loco in question, but off the top of my head it’s ‘Q’. HTH.