By Mark L. Chambers from "Mac OS X Lion All-in-One For Dummies"
Not that it happens very often, but what if the wrong application launches when you double-click a file in Mac OS X? Not a problem: You can change the linked application from the Info dialog. To choose another application to pair with a selected file:
1. Click the Action button on the Finder toolbar and click Get Info to display the Info dialog for the item.
2. Click the triangle next to the Open With heading to expand it.
3. Click the pop-up menu button.
Mac OS X displays the applications that it feels are best suited to open this type of document.
4. Select the application that should open the file.
To go completely hog-wild and choose a different application, select Other from the Open With pop-up menu. Mac OS X displays a Choose Other Application dialog, where you can navigate to and select the application you want. (If the application isn’t recognized as recommended, click the Enable pop-up menu and choose All Applications.) After you highlight the application, click the Always Open With check box to enable it and click the Add button.
If you don’t have an application that can open a specific file type, you can also opt to search the App Store for an application you can purchase to open it — choose App Store from the Open With pop-up menu. (A sometimes pricey option, of course, but certainly convenient!)
5. To globally update all the documents of the same type to launch the application that you chose, click the Change All button.
Mac OS X displays a confirmation dialog asking whether you’re sure about making this drastic change. Click Continue to update the other files of the same type or click Cancel to return to the Info dialog.
