Please be more specific and clear in your questions. I assume that your title is asking, "How do I set the default part, assembly, or drawing template via a macro?" But I'm not sure.
Your body is not only talking about a different topic (the Property Tab Builder) but it is unclear what "set a particular property tab builder files to part files" means.
Please read this so that you can "help us help you": How to ask a good question in the API forum
In the picture i posted it shows a drop down menu.
i want to know if a macro can be used to change that from one .prtprp file to another .prtprp file