Revenue per customer does not look correct. How can I verify revenue per customer?

Click on the Customers tab.  Here you will see a full list of customers included in Revenue.  You can also see all the invoices issued to these customers. 

See more information in this article: What to Do if the System is Not Recognising Revenue Dates Correctly; How to Change Invoiced Revenue Start and End Dates 

Also see On the 'Customers' tab, why are there small differences between the invoice level detail and total revenue? 

Multi- month invoices are automatically recognised by the system and spread over the time. See How ScaleXP Allocates the Spread of Revenue and Determines Deferred Revenue Amounts