How to Change Settings to Open a PDF File. A Portable Document File is a type of file that uses an open standard across different computer platforms and programs.

Different formats can also make managing several documents cumbersome. Combining these documents into a single PDF file may be helpful for personal or professional use, to deliver simplified, ...

How to reduce PDF file size on a Mac computer with Preview 1. Open the PDF — if Preview isn't your default app, right click the PDF, then select Open with followed by Preview.