Buttons for changing task statuses
From Planfix
You can use buttons to change task statuses. Each status has its own button. You can set up status transitions using buttons in the section Account management — Task processes — Process:
Then Process — Status set:
Click the desired status and go to the additional settings menu. In this menu you can set up options for button display. If you select "Display in menu":
then the button you create will appear in the task card menu: