When you add coverage clips to a report, either in one or multiple Sections, we'll total up all the numbers for all the clips in the Metrics Summary page.
If you'd like to see just the metrics for a single Section of coverage, you can create a new report and quickly add those clips to see just the metrics for the selected items.
First, create a new report in your account (we'll call this the metrics summary book) by clicking on the "create new report" button from the main Reports page, or when you're inside a folder.
Open your original report and the section of coverage you'd like metrics for and copy them over to your blank report.
You'll now have a report with a metrics summary just from the clips you copied over. You can even take a screen grab of the metrics summary page and insert that as a custom slide to your other book.
Alternatively, you can now share all your reports in one Folder share link with your clients. So you could try making individual monthly reports to get those monthly metrics breakdowns. You can still create a summary report from those monthly reports too and invlude that to give an overview.