In this configuration activity you could maintain the document splitting method which will be actively used.
Transaction: S_AL0_19000075
IMG Path: Financial Accounting (New) -> General Ledger Accounting (New) -> Business Transactions -> Document Splitting -> Extended Document Splitting -> Define Document Splitting Method
Table: FAGL_ACTIVEC, T8G01, T8G01T
When you enter into the transaction you will have to choose or maintain method for document splitting.