If you’re seeing the pop-up ads on every website you visit, or if your browser’s homepage has been changed unexpectedly, it’s possible your browser has been infected by a type of malware known as adware. Adware injects ads into web pages in such a way that they can't be blocked. The only way to get rid of these ads is to remove the malware. You’ll find the basic steps for finding and removing adware and other types of malware below. (Don't forget, AdBlock can help protect you from malware!)
How To Check For Malicious Extensions
How To Remove Malware From Your Device