Windows 10 has a habit of reverting all the file associations back to default settings when it updates. This means that even if you specifically set certain types of files to open with certain apps, they may switch back to the Windows defaults.
This isn't ideal, especially given that the default Windows apps for many tasks are inferior to third-party alternatives. Luckily, there's an amazingly simple fix for this, allowing you to restore your preferred associations.
Open Windows 10's Settings app, and under the System tab, you should find a category marked 'default apps'. From here, you'll be able to pick what kind of app opens various kinds of media. For example, you change it so that music is played in Windows Media Player rather than Groove Music.
You can even get right down to the minute details, changing which apps handle specific file extensions. This means that you can set different programs to open specific image or video files, for instance, while still having the majority handled by a different application.