or you can do like this

Moving files to the Virus Chest
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=501#idt_03

Submitting files from the Virus Chest to avast! Virus Lab
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=501#idt_07