Try Aegisub Menu Select: >Subtitle >>Styles Manager >>>Edit (Current Script) 1. Opaque Box (Check) 2. Outline Color (Optional) 3. Apply, Enter & Close 4. File>, Save Subtitles As or edit sub file: Style Lines, [v4+ Styles] section Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, Tertiar...