Find the pattern before changing every cue
Choose a clearly spoken word near the beginning and one near the end. Note when the word is heard and when its subtitle appears. If the difference is about the same at both points, use a fixed offset. If it grows, investigate a frame-rate mismatch, a different video edit or missing material. An offset alone cannot fix every kind of drift.
Fix a constant delay
A positive offset moves subtitles later; a negative offset moves them earlier. In this illustrative example a word is heard at 10 seconds but its subtitle starts at 12 seconds. Apply -2 seconds, then check another cue. In the subtitle shifter, cues ending before zero are removed and starts before zero are trimmed; read those notices before downloading.
Fix drift only when you know the source rates
The shifter applies source FPS divided by target FPS, then adds the offset. For a known 24-to-25 FPS speed change, a subtitle at 100 seconds becomes 96 seconds before any offset. Do not choose those values just because they seem common: verify how your video was converted, and compare the end of the recording as well as the start.
Handle a cut or shortened video
If a section was removed halfway through the video, the remaining cues may need different corrections on either side of the edit. Split the subtitle file into matching ranges, adjust the affected part and merge tracks with explicit offsets. For a standalone clip, extract the same time range and reset subtitles to zero.
Check malformed times and local mistakes
Use the subtitle checker to catch reversed or invalid ranges, and optionally enter the video duration. Overlapping cues are warnings because some overlapping dialogue is intentional. Correct isolated errors in the subtitle editor instead of shifting the whole track. Keep a copy of the source before replacing it.
Verify the file you will actually use
Download the corrected SRT or VTT and open it with the target video. Check the beginning, a middle scene and the ending. If you need styled captions on the video itself, carry the corrected result into the video workspace, choose the matching source video and render an MP4. Check the rendered result before posting.