Hatch All Existing Structures

This change will be made in the Phases dialogue, found on the Manage tab.  In Graphics Overrides, change Existing Cut Pattern to your preferred Existing hatch style.  Options:
Change the Projection/Surface Pattern if required.
Change the color of Surface and/or Cut lines to black, if desired (This will not entirely override linked models that are already shaded or Underlayed)

Alternately, change the materials: