If selected, Enable Plug-Ins lets plug-ins such as Flash and Adobe Reader. Quit and re-launch Safari, then open a PDF file directly in the browser when you do, the PDF should open using your new Adobe Reader plug-in. The four options here determine what actions Safari takes with common Web content.
Now, want to open PDFs in Safari using a fresh Adobe PDF Viewer plug-in? Try this: When it does, go ahead and release the COMMAND and TAB keys. Note: Make sure to back up your Mac before messing around with any system files. Drag any old Adobe PDF Viewer plug-ins into the Trash, then restart Safari.
