Bulk change allows applying changes of the same type to several tasks at once. It is available for a few standard and all custom fields.
To perform bulk changes, click on the Bulk change icon 1 in the top left corner of the project grid.
Tick the tasks you need to apply changes for 2. It is possible to make bulk changes by: Assignee, Status, Priority, task color, and all Сustom fields if you have added them (e.g. Labels in our case).
Select necessary fields on the right-hand menu 3 and click on Apply changes 4.
Note that you can also delete chosen tasks by clicking on the Delete tasks button 5.
With this feature, you can select multiple tasks from a list (multiselect tasks). That way, if you tick a parent task, all its subtasks will be selected. If you tick the first box above the task list, all the project tasks will be selected.