How to edit a report template
From your root control panel, navigate to the "Templates" section.
Click the "Reports" tab.
Click any template to open it for editing.
Apply your desired changes within the report editor, then click the arrow beside the Save button on the top right hand side and click "Save & Exit".
Note: Changes are no longer applied instantly to reports that are based off from a template. If you want to roll out template changes to regular reports, you'll need to reapply the template to those reports.