From the script section:
You can edit the script by clicking on the "Edit" option and navigating to the "Script" section.
Here, go to the chapter you would like to edit, then click on the 3 dots on the top right, and you will get options to:
Duplicate chapter - This option will duplicate the current chapter.
Add chapter before - This option will add a chapter before the current one.
Add chapter after - The option will add a chapter after the current one.
Delete chapter - This option will delete the current chapter.
Click the "Save changes" button to apply and save the changes you made.