I guess you mean you want Webroot to scan all files on removable media when it is attached.

I am afraid, there is no way to configure it other than enable the USB Shield.

 

Now, how the USB Shield works indeed, is the question after all.

I do not see signs of Webroot auto scanning all the files on removable media.

All you can do for it is to rigth-click on the USB drive in Explorer and select 'Scan with Webroot'. This will scan all files for you.

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