Reconcile Account Level Reserve

Background: I am an accountant in a small company so I need details not high level overview.

How do I reconcile the Account Level Reserve? We have excellent performance metrics, so I believe the only reserve is for “7+ Delivery Days” to guard against returns. But how do I prove my assumption to my boss? Is there a report on the reserve? A report of delivery dates?

Everything else seems to have a report. There should be one for reserves.

Thank you