To design the accounting reports you need to be logged in to XERO. Then you need to select from the menu Extensions -> G-Accon for Xero -> Reports -> Report Designer -> Design Accounting Reports and then select a table (Account, Invoices, Purchase Orders, and ect. )
There are multiple accounting reports you can select from the drop-down box which allow you to create reusable templates for later on usage.
G-Accon for Xero also provides you with the ability to set up multiple optional settings to meet your business needs.
G-Accon Help Center 