The element pens and line types are taken from the object itself so you would need to change the settings of the beams in the model to the line types and pen colours you would like. However that will obviously affect the appearance on plan/ section. If you want the schedule to appear differently you can create a graphic override and apply it to the schedule. We use this method all the time for doors. If you select the preview image in the schedule and look at the settings down the left hand side of the schedule window you may be able to override the lines and pen colours there too but for the life of me I can’t remember without opening Archicad.
Lee Hankins ArchiCAD 4.5 - Archicad 26UKI Apple Silicon 4032 macOS Ventura (13.1)