Where can I update the template for a custom SQL report?

https://preview.redd.it/yxzizz7ewhng1.png?width=1739&format=png&auto=webp&s=7207fd22574019af42ffa0cdb260465759334e15

I can find the report under Custom Reports. I just can't find where to edit (or even make a replacement) report.

Thanks!