An easier way to apply new textures to material zones which share the same texture map, on a PC, right-click on the workspace in the Material Room for the pull down menu and navigate down to Select All.  This will highlight all nodes, including the PoserSurface node, present in that particular zone.  Perform another right-click and navigate to Apply to All.  A warning window will popup, just click OK.  All the zones will become populated with the new textures.  Go the Wacro panel on the right-hand side of the Material Room (if not visible, click on the Klingon toothpick), hold down shift on your keyboard, and click on the Remove All Unattached Nodes to clean out the zones of any extrenuous nodes. 

Caution:  This should only be applied to props or models that share the same texture map, i.e., the baseball cap.  Applying to models, such as characters or large multi-mapped structures or objects, will override all their default textures for the one you are selecting.  Disasterous if you are looking at many, many zones.