Are you trying to ask us why your laptop is constantly getting infected with viruses?
In addition to using AVAST, you could also consider enabling the Firewall, installing Malwarebytes on your laptop and using Ad blocking add-ons for your web browsers.
Once you post the details here, we should be able to recommend specific solutions.
When I connect an external microphone to the jack, it is not working. I can see it in the "Sound" tab, but the levels is very low. I have tried with several microphones.