Bank info will be included on customer invoices prints/pdf's by adding this in the Docref field on the 
Bank Account Info.
The DocRef field in the Miscellaneous area, defines where the bank account number is going to be used.

Here one can choose several documents where this information is to be included.

The invoice (pdf) in for example EUR will have an account number for the euro account bank, according to the respective currency.  If there is no EUR account that has the Docref=CIN defined, the system's currency will be used - for example a NOK account.

It is possible to add IBAN and Swfit too in the DocRef field and the bank account information will appear on the print here as well.

More information regarding Bank Set-up can be found here:
Bank account