How to Set Subtitle Font Size

The size of soft subtitles cannot be adjusted and is controlled by the player. The size of hard subtitles can be adjusted by modifying the Hard Subtitle Font Pixels size in Menu--Tools/Options--Advanced Options, which defaults to 14.

Control the Number of Characters in One Line of Subtitles

By default, one line of Chinese, Japanese, and Korean characters has 30 characters, and one line of other languages has 60 characters. You can adjust this by modifying the Number of Characters per Line for CJK Subtitles and Number of Characters per Line for Other Languages in Menu--Tools/Options--Advanced Options.