In STEL Order you can associate the bank account to different payment methods, such as transfers, bank deposits or deposits in account, among others.
From your profile go to Settings > Basic settings > Data list > Payment methods > select the one you are interested in or create one in New, add the name, for example "Bank Deposit" along with the rest of the data. Check the box Associated with bank account and Save.
OK! When you make a document, it now gives you the option to choose the payment method with your bank account or to define a default one.