Subtitle files are release-specific. For a version (often associated with groups like YIFY or RARBG), you need an .srt or .smi file that matches that specific encode to ensure the timing is correct. Top Subtitle Sources :
OpenSubtitles: One of the largest community-sourced databases for film subtitles. subtitle The Sixth Sense 1999 1080p BrRip x264 ...
YIFY Subtitles: Specifically tailored for "YIFY" or "x264" movie rips. Subtitle files are release-specific