Saving changes to the diagrams you create is easy. As explained in this guide.
To save changes you make to the diagram click on the SAVE button found in the toolbar of the diagram editor.
Look out for the ‘You Have Unsaved Changes’ message found on the top right-hand corner of the toolbar for unsaved changes.
When leaving the web browser and diagram editor you will be notified by the following message ‘Are you sure you want to leave? You have unsaved changes’.