Drag a teammate onto a task to assign them, then double-click their avatar on the card to set their contribution priority.
Assign a contributor
Assignment is drag-and-drop, not a form field. Drag a person's avatar from the sprint roster and drop it on a task card to add them as a contributor. A task can have more than one contributor.
Set contribution priority
Double-click a contributor's avatar on a task card to open the priority dial. Choose Top, Second, Third, or None. Priority ranks a task's contributors relative to one another — useful when several people share a task and you want to note who's primarily responsible for it.
What to do about it
Reserve Top for whoever should be treated as primarily responsible when a task has multiple contributors — it's what a manager or teammate should check first when following up on progress. See Manage the Sprint Roster for adding someone to the sprint itself before you can assign them to a task in it.