You can do it on an individual file type basis or change all of them from one location. The three-letter designation next to that is its file type. Look for Type of File at the top of the window. If you aren’t sure which file type you want to change the association of, right-click your desired file and click Properties from the resulting menu. Although you can get around it using the “Open With” command, there is a way to make sure you don’t have to do that every time: Learn how to change file associations. If you’ve ever run into the problem of Windows trying to open up a file in entirely the wrong application, you’re not alone.