In Windows 10, to change which app opens a certain file extension by default, please do the following:

Step-by-step guide

  1. In file explorer, Navigate to one of the files that is of the type you would like to change
  2. Right-click the file
  3. Go to Properties (usually at the bottom of the drop-down menu
  4. Click the Change... button
  5. Select the new app you would like that file type to open with
  6. Click the Apply button at the bottom, then click OK and that file type should now open in the selected application by default

There is also a page under the Settings app, under Apps > Default apps