https://userapps.support.sap.com/sap/support/knowledge/en/3558850
3558850 - How to change the default layout for the reports FBL1N/FBL3N/FBL5N or FAGLL03 | SAP...
There is a requirement to set/change the default layout for the reports FBL1N/FBL3N/FBL5N or FAGLL03.