If you’ve set your Nexus 7 or other Android device running Jelly Bean to use a specific app to open certain files, you might want to change it later. Changing the file associations is easy, here’s how.
For example, here I associated PDF files to open with Aldiko reader. I would rather it opens with a different program, and need to get rid of that association. To do it, go to the Settings menu of your Nexus 7 – it’s in the main Apps menu.
You’ll find a list of installed apps. Select the one you want to clear file associations for. In my example, it’s Aldiko.
In the window that comes up, find Launch by Default and tap the Clear defaults button.
Now file associations and actions are cleared and, when you click one of the files which were previously associated with the app, you’ll be asked what app you want that file opened with.