Uncheck any tracks you don't want (like the original English track, if you want to save space). Select the Hindi track, and under Properties on the right, set the "Language" to and "Default track flag" to Start multiplexing

None required at this time.

| Issue | Solution | |--------|----------| | Audio out of sync | Use delay values (±250ms steps) in MKVToolNix or VLC's track sync option (press F / G keys). | | Hindi track not appearing | Remux into MKV container (MP4 sometimes ignores secondary tracks). | | File size too large | Your Hindi track is lossless (FLAC/WAV). Convert it to before muxing. | | No sound after muxing | The Hindi track may be encoded in AC3/EAC3 which lacks on some devices. Convert to AAC. |