Priceless Extension

An extension called PriceLess appeared in all my browsers. It makes weird ads appear in pages, new tabs and even tried to download software I hadn’t authorized on its own. If I try to remove the extension, it comes back after I restart the browser.

I know Avast’s browser cleanup removed the extension from my boyfriend’s computer, but it doesn’t detect the extension in mine, what should I do?

Attach your basic logs. (MBAM, FRST and aswMBR…!!)
Instructions: https://forum.avast.com/index.php?topic=53253.0