Automatically trim the audit log for this site? (SharePoint Logs)

Is there a way to Turn Off the "Automatically trim the audit log for this site" for a specific site with in my SharePoint Online Collection or is it only possible at the root level?

Also, is there a reason the option is greyed out for me event if I am the Site Owner/Admin?

I am trying to Achieve some analytics on a specific Site that we have.