Hi David,
I am sure you have answer for your question already. But just in case others will like to know the answer to the question - Using NWBC - go to cash manager, then manage bank accounts. Click on Account List. Select/Click on the bank account you want to assign GL Account. From here click on the "Connectivity Path" Tab. Then click on Edit to be in change status. By the left hand corner you should see add - click on "Add. You should now be able to see the "House Bank Account Data" with the field G/L Account.
I hope this help resolve your issue.
Regards,
Andrew F