To copy a Narrative that has been shared with you, so that you can run or change it, you can use the blue “Copy This Narrative” button at the top of the Narratives panel (or, in View-only mode, at the top right of the screen). This will copy the Narrative that you are currently viewing (which is marked with a green dot in the list of Narratives). You can choose a name for the copy (or leave the default name, which is the original name with “Copy” at the end).