System Defaults screen requires payment information under Financial Transfer mode
The System Defaults screen requires that you save defaults against the default supplier/customer payment types as well as the default banking accounts. The problem is that Financial Transfer accounting configuration companies won't have these set up but may still wish to set default screen sizes. Setting default screen sizes is prevented unless valid payment types and banking accounts are entered. This is something that we need to address via programming. The current design for the System Defaults screen is really only accommodating of full DBA Financials accounting setup.
The current work-around for this problem is that you will need to set up dummy payment types and a dummy banking account in order to save the default screen sizes in System Defaults. You will most likely need to switch to DBA Financials accounting configuration under (Admin > Accounting Configuration), set those dummies up, and then switch back to Financial Transfer. The payment types screens are under (AR > Accounts Receivable Setup > AR Payment Types) and (AP > Accounts Payable Setup > AP Payment Types). The banking accounts are set up under (Bank > Banking Setup > Banking Accounts). Again, for Financial Transfer customers you'll need to least one payment type against both AR and AP as well as a banking account entered. This should allow you to provide something for the defaults in the System Defaults module.