1) In Finder, locate a file of the type that you wish to manage. For instance, if you want to change the app that opens JPEG files, find a file with the .jpg or .jpeg extension. Right-click (secondary click) the file and choose Get Info.

2) If the "Open with" section is not expanded, click the disclosure arrow to expose the section.

3) Under the "Open with" section, choose the desired default application. Then, click the Change All button.

4) Click Continue to confirm.

5) Close the file properties window.

Outcome

You have successfully modified the default application for a given file type. Any time you open a file of that type, it will open in the application that you specified.