Instead of going through each individual task to reassign tasks or change dates or statuses, use the options menu on the section header to change this in bulk.
Bulk updating due dates
Give all items the same due date by choosing Set Due Date from the options menu “...” to the right of the section header.
Bulk updating task status
Assign all items with the same status by clicking on the options menu “…” and then select Change Status.
Bulk updating assignee
Assign all items to the same person by clicking on the options menu “…” and then select Assign to Me or Assign to Colleague. Select a colleague and all items will be assigned to that person.