1) Select the Label Tool
2) Select the door/window tool from the Content and Preview
3) Select the type of marker and adjust its attributes according to your needs.
4) Select your door and windows and from the List and Labelling pull down click the label windows option
Hope this helps.
ArchiCAD since v9 to latest
iMac, Windows 10
If you are not already a member of Archicad Select, you can for a short amount of time at a small fee, then download all the Quick Tips. Quicktip 2008#08 answers this question and 2007#09 answers the site orientation question.