Usually a mismatch between the Frame Rate (FPS) of the video and the subtitle file (e.g., a subtitle file timed for 23.976 fps played on a 25 fps video).
Subtitles that are too small to read, bright neon green, or stuck at the very top of the screen are often the work of hard-coded formatting gremlins. subtitle Gremlins
If you want total control, convert your file to a "clean" .srt format. SRT files are plain text and usually let your TV or app determine the font size and color. Final Thoughts Usually a mismatch between the Frame Rate (FPS)
Tackling the "Subtitle Gremlins": Why Your Captions Go Haywire bright neon green
