When you’re editing a play, playbook, formation, or playart (content) the save and edit icons at the top right of the designer:

will change based on the status of the content.  The top save button will turn yellow when there are unsaved changes and the edit button underneath it will be yellow if the content isn’t published and is not visible to other authors:

Clicking the save button to save your changes will remove its yellow background and clicking the edit button and marking the content status to “Published” will remove its yellow background.