Hello!
New Admin here... please be gentle 
This morning off-hours, we implemented changes to our master workflow used by approximately 25 scrum teams. Post implementation in production, the new statuses and swim-lanes were available but for some reason numerous closed stories were re-opened.
1. Is there a way to bulk close the hundreds of stories which re-opened?
2. From a Lessons Learned perspective, what should we do in the future to prevent this from happening?
Thanks in advance - Tom