Users are now able to change the priority of items in the backlog by moving them around on the Kanban Board. Is it possible to not let them do this?

Hi all, 

The priority of items in the backlog are not being honored when dragging items across columns on the Kanban Board. 

We used to be able to do this and it was useful to keep track of the order of items. Now users can drag across and they have to remember where it was in the order of the backlog and drag it there. It used to just "snap" into it's place in the order. 

Is there a setting somewhere I can change this? Was this functionality changed? 

Thanks