If your subtitle is off by a few seconds, you can fix it manually in real-time or permanently. Option 1: Quick Sync (VLC Media Player)
If you only want translations for the Na'vi language parts, search for "English Forced" subtitles. subtitle Avatar.-.Extended.Collectors.Edition.2...
Because this edition includes roughly 16 minutes of additional footage, standard theatrical subtitles will not sync correctly. If your subtitle is off by a few