Apply Template to an existing issue easily!
Step 1
Click "Apply template" menu item under Issue menu.
Choose "Apply Template" action
Step 2
Choose Template and click "Apply".
Step 3.
Jira Issue will be updated with data from Template.
Go to your Jira issue
Open "More" menu
Click "Apply template" menu item
Choose template from given list
Then Jira Issue will be updated with data from Template
On Server instances - Subtasks will be autopopulated with "Apply" method as well