Windows has long provided an interface for configuring which apps are used by default to open certain file types or handle particular protocols. In Windows 10, this interface has been updated and simplified dramatically. But most users will probably want to change at least a few of the defaults.
In Windows 8.1, Default apps had two interfaces: a simple one in PC Settings and a more advanced version in Control Panel. Windows 10 works similarly, though you can now manage more of this functionality from a single interface. You access the interface by navigating to Settings (WINKEY + I), System, Default Apps.
On a clean install of Windows 10, each of the defaults will be set to built-in apps. (Microsoft will retain some—but not all—of your customized defaults on an upgrade.) That means Calendar, Mail, Maps, Groove Music (for music), Photos, Movies & TV (for video player), and Microsoft Edge for web browser.
Chances are, you want to change some of those. Doing so is easy: Just click the app in question and choose a new option from the list that appears.
If you’re familiar with Default Apps from previous Windows versions, however, you may know that picking a default like this won’t necessarily handle every possible situation. For example, if I change the default photo viewer from Photos to Photo Gallery, it will only associate the most common picture file types with Photo Gallery. And some, like BMP and GIF will actually continue to open in Photos. That’s annoying.
To fix this, you need to go old school. Click the “Set defaults by app” link at the bottom of Default Apps to display an old standby: the Set Default Programs control panel. Then, navigate down to the app you really want to use all of the time for certain functions. In my case, I want to use Photo Gallery to view all picture files, not just some of them. And as you can see, Photo Gallery only has 8 of 34 possible defaults, despite the fact that I literally just configured it as the default app for photos.
To really set this app as the default, click “Set this program as default.” Or, use “Choose defaults for this program” to pick and choose. You should examine this for any defaults you change.
Note: You can continue to open files—and make basic default changes—with whatever app you wish on the fly as before. Just right-click and choose “Open with.”