I just reinstalled OS an hour ago by deleting everything on "Macintosh HD" and on the "Apple SSD". When I got my computer back up and running I got on safari and my browsing history from my computer days before I deleted everything was still there as well as my bookmarks, favorites and safari settings. I'm getting ready to sell my macbook in a few months and when I delete everything I don't want a single thing related to me to be on the computer. What did I do wrong/could do different?