Windows 7

1. Click on the Windows logo to open the Start menu
2. Select Control Panel.

3. Ensure that you viewing the control panel by 'category'
4. Click on the link labeled Programs. 

5. Click on the link labeled Set your default programs.

6. In the Programs list on the left side of the window, select the program you would like to set as default

7. In the right side of the window, click Set this program as default.

Windows 10

1. In the search bar, close to the start menu, type 'control panel'. 
2. Open the control panel desktop application.

3. Ensure that you viewing the control panel by 'category'
4. Click on the link labeled Programs. 

5.  Click on the link labeled 'default programs'

6. Click on the link 'set your default programs'

6. This will open a new window. Now, scroll to the type of application you wish to change and click on the default program. 

7. This will provide you with a list of other applications available to use. Select the application you wish to use as your default.