You have two options here:
Redirect an assessment to a student or Update the assignment parameters.
See this article about Redirecting
When you assign any assessment make sure to give a reasonable cushion between the access date (when student can start) and the due date. This helps you prepare for any unforeseen issues with the assignment that may require you to adjust the assignment's due date/time (or make edits/changes) before it closes on your students.
Note: You can change the due date for only those assignments that are in "In Progress" or "Not Open" status.
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However sometimes, you need to update the assignment and make the due date either earlier or later. Please follow the steps below to change the due date of the assignment:
1. Go to Assessments Menu and locate the assessment. Click on the assessment, hover over the three dots, then click on "Update" from the Action drop down.
2. Change the due date for the assignment. Please ensure that the date and time is in future.
3. Click on the "Update" button in the upper right corner and the due date of your assignment will be updated.