Colouring an image trace

Is there a way to apply the same colour to a bunch of different sections of an image trace all at once (ie. without changing each little piece one by one)? I know it's possible to select all bits that are already the same colour and change their colour but I'm trying to find a way to make sections that are different colours the same colour without having to do it one tiny piece at a time. I have tried selecting multiple vector graphics at once using shift + click and then trying to colour them, but when I do this the fill icon gets a question mark on it and grays out.