Hello and welcome to Android Forums. Hopefully I can help you with your problem.
Try using the Joe VLC Player available on Google Play. It is the best one I've found that enables the subtitles when viewing through the HDMI out to your wide screen. That app should fix you right up. If not, please repost with a list of the apps you've already tried that are not displaying the subtitles.
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If you have any other questions regarding your device, I invite you to join Android Forums. We have many sections for specific devices which contain a wealth of information.