AutoCAD Inventor :: Changing Part Properties In Assembly?

I have often right clicked a part in the browser of an assembly and edited its properties. This may include stock number, material and adaptability.

Drawings of these assemblies seem to update accordingly. At least initially.

I have noticed often several sessions later, the same properties have defaulted to their original value.

And I came across the statement in the corrections attachment.

What does the highlighted sentence mean, exactly? And which properties respond to a change at the part level when edited in an assembly?

Using Inventor 2012 Windows 7 Dell Precision dual EH(quad core) @ 2.13 GHz 4 G Ram