Changing the default indicator for bank charges changed from it current setting from 'our' to “s

Our Service Delviery team wants  the default  indicator for bank charges changed from it  current setting  from 'our'  to “shared”.  They think this field is populated by the file created by Oracle when generating the file which is loaded into both Lloyds bank and Citibank.  Currently the AP Payments Service Delviery team is manually changing this for each transaction which they say can be time consuming.

I'm having trouble finding how I can do this for them. I've had a look in Payments Options and I can only see a check box that allows you either to deduct changes to a payment or not. Is this anything to do with the issue.  I've also looked at our different back accounts but I can't see anything in their set up that would apply to this