Click on the assignment title on your course page.

Click on the More dropdown menu and select Overrides.

Choose either a single user override or a group override and click the Add user override button.

Click on the dropdown menu in the Search box and select a user. The user will appear in gray above the search box.

Change your assignment dates for that student. Below, the student was given a few extra days and the cut-off date extends an additional day for good measure.

Save and enter another override or just save.

The student and the override dates will display after saving.