Changing Appearance of a part's face within assembly

Hi. I'm trying to change appearance of a face of a specific part in an assembly, in this case the dome face on part HLMP-1790<2>.  Note that there'are multiple HLMP-1790 and I'm only interested in changing the second instance (<2>).  As shown in screen capture, under 'Selected Geometry', it has Face<1>@HLMP-1790-2 selected. yet, all other HLMP-1790's dome face also turned green.  Is this normal behaviour? or is there another way to achieve this?

Thanks.

SolidworksGeneral