There are two settings you can modify to change the order of videos in a story. From your Dashboard, click on My Stories, and then the story’s Settings menu. Then modify one of the following settings:

Show my video first: Select Yes to always play your video or text prompt first in the story.

Playback: Select the playback option (Chronological, Latest First, Popularity, or Custom) that best fits with your needs. 

• Chronological: Plays the videos as they are recorded/uploaded
• Latest first: Plays the most recently added videos first
• Popularity: Plays the most liked videos first
• Custom: Plays whichever order you decide (you can change this on the Manage menu by dragging and dropping the videos into the order of your choice)