It is easy to create a Sales Invoice.
Just select the customer name from a list. You can search with part of the customer name or phone number if the list is too long.
Choose the stock account storing the items related to this sales transaction. The software will automatically deduct the quantities and (First-in-First-Out) cost values of these items from the stock account and reflect in the inventory level screen.
You can easily select the items for this transaction from the following screen:
It is almost the same for creating a Purchase Order to record the purchase of materials or goods.