Make sure you follow the guidelines provided on right hand side panel for pre required settings of these reports.
This report shows Average Monthly/Daily billing for all environments. Age of billing history is one year.
This report shows summarized cost for all application and environments. Select Application and environment to view report, choose time period by selecting dates.
Cost By Application
This report shows billing information per application and its environment basis.
Cost By Service
This report shows billing per service such as server instance, databases, etc.