Applying changes to a prefab not working...?

Hi guys, I have just created an object as a prefab (geometry from Maya) and have duplicated it around the scene. I want to add a Rigid Body to the prefab and update the rest - only it doesn’t seem to be working, the menu option is grayed out.

Any ideas?

Ahh, this is because you’re working with a different kind of prefab, one that is made directly from an asset file. You should make a new Prefab in the Inspector, then drag your GameObject on top of the new Prefab.

More info is on the bottom of the Prefabs page in the Manual: Unity - Manual: Prefabs