Open PDFs with Preview by default (Mac)
If you would like to have PDFs handled by Preview, and not some other program, follow these steps:
1. Open Finder, and highlight a PDF file
2. Select File > Get Info (or press command + i)
3. Within the File Info window, click "Open With" (near the bottom of the window)
4. If something other than Preview is listed under "Open With", click the drop-down menu and Select preview
5. To change preferences for all PDF file handling, click the "Change All" button.
All PDF files should now be opened by Preview.