When creating a sales invoice you can choose to select the Bank details to display in the drop down box below the Summary box. You can set a default bank account for all customers on the Settings > Configure system > Invoice themes > Invoice preferences menu, or alternatively you can set a default bank account for an individual customer.
Navigate Money > Bank Accounts and select the Edit link against the appropriate Bank Account.
Fill in the Account Number, Sort Code, Cheques payable to and, if applicable, IBAN & SWIFT numbers, to be shown on invoices.
To choose a default bank account for all sales invoices head to Settings > Configure system > Invoice Themes > Preferences link and select the Default Payment details for all invoices and select Save at the foot of the screen.
To choose a default bank account for a specific customer head to Contacts > Customers and click on the Edit contact link beside the appropriate customer name. Under the Customer invoice defaults tab select a Default bank account and hit Save at the bottom. The customer default takes priority over the preferences default on invoices.