By default, Canvas will set your quiz for everyone in your course. To create the quiz for a specific student, click the Everyone remove icon [1], then start to type in the name of a student [2]. Search fields are dynamic, and you can search for students by first or last name. When the full name appears, click the name. Lists are not scrollable.
You can include more than one student in the To field as long as the students are to be assigned the same due and availability dates.