This can be amended in the Smart Post Maintenance, please see below the best way to do this.
Note (NB)
Commas can not be used in the description as these characters are used in a different way in Progress and the line will split down onto different lines..
From the Main Menu go to SmartPost Maintenance.
Select the code you are using in the Desktop when creating the slip.
Click on UPDATE.
Change the Bank Code at the bottom to the required bank you need.
This applies for all changes that need to be made in SmarPost eg Amount.
Select SAVE.