Changing multiple due dates can be a daunting process, but by using dates report, it can make the process much more efficient by putting all of your due dates on one page!
Step 1: In your course in Moodle, navigate to the administration block, and click Reports. This will show you the drop down menu that includes the dates report.
Step 2: In the drop down menu, click Dates.
Step 1: Choose the type of activity you want to change the due date of from the drop down menu located under Activity type. This will list all activities of that type.
Step 2: Click the down arrow next to the course section you wish to change due dates in, or click Expand all to view all course content of that type of activity.
Step 3: Check Enable for each desired category (Open the quiz, Close the quiz, or Expect completed on) and use the drop down menus to adjust due dates.
Step 4: Click Save changes.