Change a hijacked Safari Settings

Problems: A hijacked Safari, it opens pop-up windows, you can not close it.

Solution:

Quit the application. Force quit if necessary.

Open it by holding down the shift key and clicking its icon in the Dock. From the menu bar, select

Safari ▹ Preferences… ▹ Privacy ▹ Remove All Website Data

You might want to run a virus scan on the infected mac.