There are a couple of options including assigning a whole section at a time or an individual question one at a time.
To do this, click on the Section name at the top middle of the page. On the right-hand panel, you can select the writer and approver. You can also set due dates. After making your selections, click the button to update. You'll see the writer/approver user initials change for all of the impacted questions.
You can check in to specific questions to ensure the changes were made. Your new writers will be notified via email.