Change the default order for comments

By default, work item comments appear in order of first dated (at the top of the work item’s comment stream) to most recent (at the bottom of the work item’s comment stream). 

Jira admins can change the order Jira displays comments in their system settings:

1. Choose Settings () > System.

2. Click General configuration from the sidebar.

3. Click the Advanced Settings button.

4. Edit the value of the jira.workitem.actions.order property by clicking the existing value and changing it from asc to desc.

5. Click Update.