Vlk
4
vlad01,
as Pavel already said, the Quick scanner (that you’re activating via the Explorer context menu) only runs until a first virus is found, and then it stops.
It was intended to be used just to make sure that there is no virus in a file/folder. If the Quick scanner finds a virus, it is recommended to start a scan of this folder using normal avast! interface (Simple or Enhanced) to detect all viruses and possibly take some further actions… 
Hope this helps,
Vlk