Every time I click something on web pages, like a link or a search bar, I get a poEvery time I click something on wr a search bar, I get a pop-up. It's usually a semi-related pop-up, like on Apple websites, I get a lot of MacKeeper pop-ups.

Every time I click something on web pages, like a link or a search bar, I get a pop-up. It's usually a semi-related pop-up, like on Apple websites, I get a lot of MacKeeper pop-ups. I let my younger brother use my laptop yesterday, and now this is happening. I think he might have downloaded something, but I don't know what it is called or anything so I don't know how to delete it.

I have a Macbook pro.

Thank you!