How to do Bulk updates of JIRA issues

If you ever wondered how to bulk change issues in JIRA, here's the procedure:

• View a list of issues, e.g. by query/filter
  
• At the top-right click on "Tools" and select "Bulk Change all <no.> issues"
  
  • The screen changes so that next to each issue there's a check box
    
• Mark all the issues you want to change and click "Next"
  
• Select the operation (e.g. Edit)
  
• The next screen (followed by choosing operation "Edit") lets you edit the issues
  • Note at the bottom that you can deselect the option to send an email per issue. Do this if you don't want to spam the list.
    

NOTE: when making a bulk edit (with or without the email notifications) it's usually a good idea to explicitly note in the comment that you are performing a bulk edit, and what criteria was used to find the issues so people who come along later and see the edit on a single issue will understand the larger context. It can be particularly helpful if you include some semi-distinct token (based on the date) to help identify all of the affected issues with a simple search, see for instance this query identifying issues with this comment.