In Safari, the default PDF-Viewer in Safari is "Preview".
Unfortunately, since I installed the Acrobat Reader, this default changed to the Acrobat Reader, which is extremely annoying.
How can I change this back to "Preview"?
Go to the "Help" menu in Safari and select "Installed Plug-ins". This will open a new tab displaying information about all of the currently installed plug-ins. Find the entry for Adobe Acrobat. Below it will be a line that reads something like:
Note the name of the file from that line.
On your hard drive you will find a Library folder. In that folder will be another folder called Internet Plug-Ins. Inside that folder you should find the file that was shown in the "Installed Plug-ins" tab. The full path should be
If you are not sure you want to delete the file, you can move it to another location. For instance, you could create a new folder named "Disabled Plug-Ins" in the "Installed Plug-Ins" folder, and move the file to the new folder.
Then quit & relaunch Safari.
Adobe acknowledges this is a "known issue" and recommends this procedure.
A thread on macworld covers this. Should work by either by removing the plugin from the internet plugins folder or by changing the settings in the Adobe Reader preferences. The plugin is pretty annoying, I never installed the Adobe Reader again.