All the subtitles are editable. You can sync them manually to your videos in two ways.
Click on the ‘Subtitle’ option on the left panel. You can find the subtitles along with the respective timestamps. The time stamps are editable, and so are the subtitles.
You can also drag and sync the subtitles from the timeline. Drag the edge of the subtitle box according to the required timing. The timestamp on the left panel for that subtitle is automatically altered.