I want the History and Comments for a ticket to go from most recent to oldest. I think that's descending order. This is what I did a few months ago. I'm pretty sure it was working. Now it definitely is not. I'm not interested in a temporary fix, i.e. click the sort button. Everybody on my team wants the most recent at the top, which is why I made the global change.
- go to Administration -> System -> General Configuration and click on Advanced Settings
- locate jira.issue.actions.order and change the value (asc) to "desc"