Is this a normal function, is there an option I can switch off?
Go to Protection/Virus Scans/Custom Scans(Open now)
Hover over ‘Smart Scan’ and click ‘More’
You’ll find Settings and Delete. Settings will give you options as to when to run and includes “Never”
I have mine set to monthly 
Thank you very much!
You’re welcome.
I don’t know if this is now the new normal for the Smart Scan.
It is only recently that the smart scan could run as a scheduled scan. As would appear to be the norm by Avast, this option was set by default. Leaving the user trying to find the way to stop it. But I really know why this is so, the Smart Scan is a platform for avast to sell other products.
Thanks for helping out in this.
The whole Settings issue in this UI, is a total bloody mess settings in three different areas.
Why the Smart Scan settings aren’t directly from the Protection > Virus Scans screen for the Smart Scan.
Whilst I’m at it direct access to settings for all scans on that screen. Users shouldn’t need to go digging to find scan settings, it is after all an integral part of an antivirus program.
+1 Agreed, it is non-intuitive.
Maybe it’s time to fulfill the promise to enhance the right click function of the Avast system tray Icon?
https://screencast-o-matic.com/screenshots/u/Lh/1566244146726-37713.png
How many years ago was this promise made, so many most people can’t recall it or weren’t even using avast when it was made.
Call me an elephant.
OK you’re an elephant, but then again my memory is still in good shape 