I use Google Chrome, (within Windows 7), but also Duck Duck Go.  I routinely clean out search history.  For some reason, I keep seeing about six previous search words when I query a website for something.  For example, I might search for a paint color on the Sherwin Williams site and when I put the mouse in the query box the words "joint pain," along with five other old searches pop up for me to select.  I have turned off "prediction" in my settings and have cleaned and cleaned old search histories, but I can't shake off these six search words.  I am going to scream if you don't help me.