How to disable auto duration in Shortcuts -> Adjust?

[tuanbs]

• My workflow is: Import video -> import plain text (already separated with line break) -> use the shortcuts to set duration for each line text.
• My shortcuts for adjust is: Set start time, keep duration [Left]; Set end, next start and go to next [Down].
• Problem is: After I press [Down], the duration for each text is 'auto duration', not 'keep duration', which is incorrect most of the time. The long duration applies for short text or long text with short duration that makes the text disappear so quick on the video. For example, with the long text of 20 words but its duration only a few million seconds causing the text disappear very quickly, which is difficult to create sub.

Could anyone tell me how to fix it? Thanks in advance.