You can set a default bank code on any Posting Type if it has a bank code field in Posting Maintenance.
Follow the steps below.
From the main menu open the Posting Maintenance program.
Click on the DEFAULT tab.
Highlight the relevant posting type.
Highlight the Bank Code in the Label and Field section.
Click UPDATE.
Click on the magnifying glass and select the required code from the Bank Code Lookup.
Click the tick at the bottom of the screen.
N.B.
Take care to select the correct bank code for the transactions type.