When you add a text comment to your report, you have the ability to make it either static or dynamic by using the switch:
Static comment will persist on the report even if you change the reporting period.
Note! Use static comments to build your report layout, like adding section breaks to a multi-source report.
Dynamic comment will be associated with the reporting period and it will need to be filled accordingly. So anytime you change a date on the report, dynamic comments will need to be refilled.
Tip! Use dynamic comments to explain the data in your automated reports. When you automate the report, you can select an option to notify you before sending it. You'll have 24 hours to fill the dynamic content.