if your pc opens the amff file, but it's the wrong application, you'll need to change your windows registry file association settings. in other words, windows is associating amff file extensions with the wrong software program.

How would the previous sentence be correctly capitalized?
If your PC opens the AMFF file, but it's the wrong application, you'll need to change your Windows registry file association settings. In other words, Windows is associating AMFF file extensions with the wrong software program.