In order to edit an assessment, select Assessments from the left of the page.

Place your mouse over the title of the desired Assessment, and click.

After selecting Edit, you will be able to reorder the items in the assessment builder, delete item(s) from the assessment builder, add additional items to the assessment from the bank at the bottom of the page, or create new items by selecting + Create.
If you'd like to edit Details about the assessment that has already been assigned, select "Assigned", hover over the three dots, and click edit. 

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