The source when viewing group reporting data in SAP Analysis for Office is a calculation view.

According to the SAP S/4HANA Finance for Group Reporting Associates documents1, in order to release data from a prior period, you must change your global parameters. Global parameters are parameters that define the scope and settings of your consolidation scenario, such as fiscal year variant, consolidation ledger, consolidation group, etc. You can change your global parameters by using the Change Global Parameters app. You can change the period parameter to select the prior period that you want to release data from.