Audio visualization dupilicated prefab not changing

Hi,I am recently learning how to make audio visualization by unity. And I have created 512 instantiated cubes to get from Audiosource and make them change in the scene. But 512 cubes are too much to see. So I change them into 8 cubes. So I duplicated my prefab in the scene. But why is my duplicated 8 prefabs not changing as the 512 cubes do?
I just drag and drop the prefab directly into the scene and duplicate them. Is this the wrong way?,