The File Associations is a feature of the Windows operating system that allows the user to create a relationship between a certain type of file and a program that supports the file. When this relationship is set up the user can then double click the file from My Computer or Windows Explorer and the file will open in the program with which it is associated.
To Change a File Association:
1. In My Computer or Windows Explorer, right-click a file with the extension whose association that you want to change, and then click Open With.
2. In the Open With dialog box, click the program that you want to use to open the file type. Or, click Choose Program to choose the program that you want. If the program is not listed, click Other to locate your program.
3. Click the Always use the selected program to open this kind of file option.
For additional information, please visit Microsoft support website at support.microsoft.com