Unfortunately no setting available. If you investigate Plesk and DR.WEB you can see the same picture. All settings are by default -- as in more software which use third party antivirus -- (The best example GFI Mail Essentials software, which manage 3 antivirus through its own interface, providing less then a half of available settings)
Also note, there must be the ClamAV update task in Plesk CP->Server->Scheduler
John S.G.