BOM dosen't refreshed.

I want to a revision drawing just changing the material stainless to aluminium.

So, I added configuration and chaged the material to aluminium.

And than, I copied original drawing, changed  configuration.

Here's the problom.

The material of the original drawing also changed to aluminium! and It doesn't refreshed to stainless

What is the problem?

Copying whole drawing was my mistake?

I think the fastest way to make material-chaged-drawing is this.