Why didn’t Avast catch the URL Safety virus on my computer. I even rescanned my computer and it still didn’t find it.
There is no one to help you here, try Malwarebytes forum
https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/
Self teach at Avast Academy:
https://www.avast.com/c-website-safety-check-guide
Detected encoded JavaScript code commonly used to hide suspicious behaviour could kick such detections up. Use Avast Online Security and Privacy extension in your browser of choice.
polonus