You are able to interact with every section of your course from this menu

At the bottom of the page you are able to see a calendar for all of the dates of assignments in your course

If you'd like to be able to see every activity at once, you can click on 'expand all' which will expand every topic

Alternatively, you can also click on this dropdown menu to filter by activity types

All activity types in Moodle are displayed in this drop down menu

Once you are done editing the dates for your activities, click 'Save Changes'

Change Assignment Dates in One View