When you open a file on your computer, the operating system decides which program launches it. A photo might open in your image viewer, a document in your word processor, and a video in your media player. Sometimes the default program works fine, but other times you want a different one to handle certain file types. This category covers how to change those defaults on Windows, Mac, and other systems.
The articles here explain how to change what opens when you double-click a file, how to pick a different program for just one file instead of all files of that type, and how to troubleshoot when a file won't open in the program you want. You'll also learn what file extensions are and why they matter when the system decides which program to use.