To change due dates the LendingDueDateDays key in the Customization Manager needs to be updated. This key designates the global Loan period for Lending.
After this has been saved, restart the ILLiad Client. All subsequent requests will have the new Due Date period applied. For already opened requests the Due Date will need to be updated manually.
For additional information, see the Atlas Systems documentation on ILLiad Customization Keys.