If I remember rightly, this has been covered before and you can edit the htm files that are in the HtmlData folder. I don't know where that might be with the ADNM set-up but C:\Program Files\Alwil Software\Avast4\ENGLISH\HtmlData is the default location for avast desktop versions.
However, I think it was mentioned that on program updates those customisations are restored to the default, so you would need to back-up your customised HtmlData files.