OS X: How to Change Default Application to Open File Type
Contributed by davak 
August 26, 2007 
Tagged: Apple Mac
If you click on a file and the wrong app opens it, you can change the default application to open that file or file type. These are the steps to both change the default app to open one specific file or to change the default app to open all files of one file type.
I frequently work with images on my MPR. Typically I just want to view an image instead of edit it so having Preview as my default app makes sense.
However, some images I know I am going to edit and edit and edit. By changing the default application to photoshop for that file, I can save a bunch of time.
Anyway, here is how to do it for one specific file only first. Below I’ll show you how to change the default application for all files of one file type.
Change Default App for One File:
1. Ctrl-click on the file you want to open
2. Click Open with
3. Select Other
4. Select the applcation you want to open the file
5. Select Always Open With
6. Click Open button
Now that one file will always open with the application you picked.
If you want to change the default app that opens all the files of one particular file type, you can do that too.
Change Default App for All Files of a File Type:
1. Ctrl-click on the file
2. Click Get Info
3. Under Open With pick the app that you want to become the default
4. Click the Change All button
5. Confirm your decision