How to identify that the track is to be enabled if the user's preferences do not indicate that another track would be more appropriate in HTML?

HTML Web Development Front End Technology

Use the default attribute to identify that the track is to be enabled, if you’re providing with two subtitle tracks for the video.

Example

You can try the following code to implement the default attribute for tracks −

<!DOCTYPE HTML>
<html>
   <body>
      <video width = "300" height = "200" controls autoplay>
         <source src = "/html5/foo.ogg" type = "video/ogg" />
         <source src = "/html5/foo.mp4" type = "video/mp4" />
         <track src = "subtitles_en.vtt" kind = "subtitles" srclang = "en" label = "English">
         <track src = "subtitles_ru.vtt" kind = "subtitles" srclang = "ru" label = "Russia" default>
         Your browser does not support the video element.
      </video>
   </body>
</html>