File associations dictate which programs are used to open certain files. You can configure your computer's file associations so that all DOC files are opened with Microsoft Word, for example, or all MP3 files with Windows Media Player. File associations are set using the Default Apps window on your Windows 8.1 computer. The Default Apps settings enable you to set file associations by category and by file type. If you're using a Windows 7 computer, change your file associations using the Set Default Programs section of the Control Panel.
Change File Associations in Windows 8 and 8.1
To change file associations on computers running Windows 8 and 8.1, swipe your mouse to the bottom-right corner of your screen, click "Settings" and then select "Change PC Settings." Click "Search and Apps" and then select "Defaults" to load the Default Apps screen. Click the current app displayed under one of the provided category headings and select the desired program from the list.
To change the association for a single file type, scroll down and click "Default apps by file type." Choose the file type you want to change and then select the program you want to use to open it.
Change File Associations in Windows 7
To change file associations on computers running Windows 7, click the "Start" button and select "Control Panel." Click "Programs," click "Default Programs" and then select "Set Default Programs." On the left of the screen is a list of all programs installed on your computer. Click the program you want to associate with a particular file type and then click "Choose Defaults for this program." Place check marks next to each of the file types you want to associate with the selected program and then click the "Save" button.