Changing Default Value of Cost Distribution in SRM 7

Hello,

we have upgraded from SRM 5.0 to SAP SRM 7.31. We now want to change the default value for the cost distribution for multiple account assignment in SRM from "by percentage" to "by quantity". In SAP ERP we have OME9 to define this. How can I do this in SRM?

Thanks in advance.

Joerg Diehl