To see who has made the last changes and published the page, go to the right upper corner and open the Options drop-down:
Looking at the page as a visitor
When you are in on-page-editing mode and looking at the site as visitor, you can always go back to CMS by clicking the blue button on the right upper corner:
Whenever you do changes to the page, Optimizely automatically saves it. From Undo? it's always possible to undo them. Remember to publish the changes on the page:
