You can edit a story that you have created
If you are an Organisation Admin, you can edit any story within your organisation
If you edit a story that is connected to an event, the story will lose its connection to the event
Steps
Go to the Story page of the story you want to edit
Press the More Options button on the right
Select Edit Update
You arrive on the Edit Story page
Make the changes you need to make
Scroll to the bottom and click Publish