FG-501E: local reports + 7 days?

Hello, I try to setup scheduled daily local reports with results for the last 7 days. So far I only get results for the last 24 hours displayed within the report file. How can I change it? I'm running FortiOS 6.0.2 Is it possible to completely customize the report at all on Fortigate? (Similar to Fortianalyzer)