I believe 4u2ges already helped. He is in an earlier timezone...:P
The trick to use props before CC3 was to have them as accessory, which is a prop attached to a character. And you can modify those, just like a prop.
As mentioned, in CC3 props were introduced, so you don't need this workaround anymore.
But I just checked and the original accessories are still there (under Accessories/Other). And you can use the Appearance Editor on them.
BTW, did you install the available Resource and Bonus packs for CC3?