Where are default apps for file types listed?
Right click on a file with that file extension, click Get Info (or just select the file and Cmd+I). Now in the Open with section change to an app you want to open that file with, now there should be a button under the place where you set the app to open with that sets all file with this extension to open with that app. After clicking the button, you might need an admin password. Here is a screenshot of the app chooser and the change all button: