You can update content that is used in multiple courses by creating master courses and clone courses. When you clone a course, there is a relationship between the original (master) course content and the clone (child) course content. If you update an assignment in the master course, the changes can be pulled (using the pull button) into the child courses.
After publishing the updated content in the master course, go to the cloned course where (in 'edit' mode) you will see the option to Pull.
When you click on Pull details will be shown (as pictured below) of the update published in the master course. If you want to accept the changes, select Update My Assignment and they will be pulled into the assignment in the cloned course.
Note: The option to pull will only appear when there is an update available.
New assignments added to the master course later can be added to the child courses. See Adding new assignments from Master to Child course for more information.
Notifications can also be sent from the Master course so all Child courses will see notification banner of updates for the course. See Working with Master/Child courses for more information