Probably the simplest way is to merge the old file into your new template. First you must open the template and make sure the story settings match your old file.
You will have two options on merge, the model or the layout, do the model first and check it properly. If it's Ok then merge the layout book and use the drawing manager to tidy up any view links.
Before you do any of this make sure your video card is on the recommended list from the wiki as this could be the cause of your problem.
You also may find it easier to include your OS and machine details in any future questions
Hope this helps
Archicad 4.1 to 26 Apple Silicon
you can't build a line