How OS x Changes the file's default open mode

As with Windows PCs, people often need to open the same file in a variety of applications on Mac computers. And, because of the environment, habits, and personal preferences, users often want to change the way a file is opened by default. In the OS X system, making this adjustment is actually very simple:

Take the PDF file as an example. Right-click on the file icon (or control-click) to see the default opening path in open with in the pop-up menu, and a list of other apps that can open this type of file.

Click "Show Info" in the menu to pop up the File Information Summary window. In the Open With Column drop-down menu, you can see a list that matches the previous one.

At this point, if you select only another app in the drop-down list, OS X will only modify the default opening mode for the current file, while the same file will remain unchanged. The key trick is to click the "Change All" button when the user chooses the desired app, and then confirm it in the prompt that pops up. As a result, all PDF files will have Adobe Reader as the default open mode.

After setting, the user can see whether the icons for other files of the same type have changed, confirming that the adjustment is in effect.