Hello everyone..

i'm new to odoo and i follow the sales, inventory and purchase modules. according to the documentation odoo handles the outstanding debits and credits of the customers and vendors. when we going to settle an invoice automatically shows the outstanding payments if exists. what are the settings or modules or any other methods to do that. because my system doesn't show it. please help me to fix this. i'm using odoo 9.0. 

thank you........!