Are you sure the options are not there?
When you press Pause, you should be able to arrow down (may need to do once or twice) which should bring up the overlay for video controls (ie. skip to next episode, etc) and then arrow Right to see Subtitles, and further right is "Audio Options".
Once you highlight Audio Options, press Ok, and then should be able to set 'Audio Languages', 'Audio Description (if available)', and 'Dialogue Boost'.
On some on my TVs depending on Prime App version, the above overlay and text is very light so hard to see the options. On others, the overlay banner has bright white text so easy to see the options.
