Using the reports page and campaign analytics, you can find the least performing templates and edit them to make them stand out.
The best way to do so is to edit the master template. This way, the system will automatically update this template across all of the campaigns in which the template is used.
To do so;
2. Find the template you would like to edit
3. Make the changes and click on Save and Close
If you don't want to edit the master template but only the template in the campaign you should follow these steps:
Go to the campaign
Find the template you need to edit
Click "unlink" and make the changes