How to Make Preview Your Default PDF Viewer
By Chad Buleen
Mac computer users may open a PDF file with the computer's Preview application. While the Preview application is the default application to open PDF files on a Mac, the default program sometimes is changed when other programs, such as Adobe Reader or Adobe Acrobat, are installed on the computer. You can change settings to make Preview your default PDF viewer again.
Right-click on a PDF file.
Select "Get Info" from the list that appears. A new window will appear on your screen.
Click the drop-down box beneath "Open With" and select "Preview."
Click the "Change All" button just beneath the drop-down list to make Preview your default PDF viewer.