How do I get rid of pop ups?

Just recently, I’ve been getting a lot of pop ups when I leave the computer. When I’m back, there will be at least 3 of them. What should I do? I’ve scanned my computer a few times already with my AVG Anti-Virus free version.

(I have a few theories of why I am getting them. I went to multiple different sites to search up song lyrics, multiple different sites to download mv’s and music, and also downloaded a ipod converter as well. )