To give the employees access to the last version of the schedule you must click on the green button "Publish" on the top right
Publishing shifts will send a notification to all the concerned employees to let them know that they have an update to their schedule.
By default, all shifts are in draft mode. That is indicated by dotted lines around the shift. When a shift is published the lines are continued.
The publish button only affects what is currently filtered. This means that you can filter what you want (lets say a specific position) and on publish what is currently on the screen.
See this article for more about filters.
You can select specific shifts to be published. See this article on how to do so with selection mode!