Go to the Moodle course with the dates you need to update.Click on the Actions tool in the upper right corner and select "More" from the bottom of the list.Under the Reports section, click on the Dates link. Select the Activity type (typically Assignment) Click Expand all in the upper right corner. Update all your dates.Click Save Changes when you have made all of your changes to the Activity type currently selected. Then you can continue on to any other activity type in which you would like to change dates.
and select "More" from the bottom of the list.
and select "More" from the bottom of the list.