The sites and scan data settings can be accessed via the burger menu. They let you control various behavior around the handling of sites and scan data.
If this setting is enabled, then a scan that is generated by the REST API (for example, by CI systems) will automatically create a new site on the Sites page unless the site already exists.
If this setting is enabled, then old scans will be deleted from the database. You can configure the age at which scans will be deleted. The default age is one year.
When scan issues are reported, Burp Suite Enterprise Edition determines whether each individual issue is new. This information is used to produce trend information about new, resolved, and regressed issues. It is also used to flag issues as false positives if they were previously flagged. You can configure how Burp determines whether an issue is "new". This can be done on the basis of: