I found the proper option in general settings, I uncheck the checkbox, but after the system restart I have this option checked again. Avast for business FREE edition on Windows 7 Pro.
Thanks in advance!
Settings must be set through the dashboard, not in the application.
Thank you for the fast reply - I will check if it works asap 
Great! It works - many thanks again
You’re welcome.
It is plain simple.
If you could do it in the application, the users could overwrite the policy of the admin and that is not desired 