how can we set a default action for all the detection of viruses to avoid avast asking me everytime what to do when it detects a virus whether to delete rename or move to chest?
These automated options are only available in the Pro version. This is a limitation of the Home (free) version that it has interactive input requirement, there have to be differences in the Home/Pro version and this is one of them, the programmers have to eat ;D
You don’t say what and when detections occur on-access or on-demand scan ?
If you are getting so many warnings, that you want to automate this process, I believe you should review your security practice - filter emails at source, delete from server rather than download them, review the sites they visit, etc.