Phil:
One approach is to create another pen set that is assigned to the drawings in the layouts, in this pen set you can change the color and weight of the pens used by the windows. You can search this forum for more explicit instructions, this issue has been raised before.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David