Why does my computer keep track of everything that I do?

My computer keeps track of every web page that I go to. Why? It’s like I have absolutely no privacy whatsoever. The search bar keeps the last search displayed on it. I have to delete it so that it disappears from the display. When I copy and paste pictures to paint, the last four pictures is boldly displayed when I click on the file tab; and there is no way to get rid of it. There is even a recent Item tab on the start menu that keeps a list of everywhere that I’ve been on the web; every document that I’ve written; every picture that I’ve viewed. Now, at least there is a “clear recent item list” that clears everything, but it’s like disarming Germany to go through and clear all of the history on my computer so that I can keep my privacy. I have my computer set that when I close my browser, all of the history is not stored, but that is just for the browser, not all of the other things that keep track of everything. Whenever I ask anybody how to stop my computer from keeping this information, it’s always the same thing. “what are you doing that you don’t want anybody to see” or, “looking at porn, huh”. No, I just like my privacy. It seem like everybody and their dogs want to pick up my computer and see what I am doing. I do keep a password, but sometimes I have to get up quickly and leave my computer. Why does the computer keep track of everywhere you been. I’m not to much into the conspiracy thing, but it makes me wander if the computer wasn’t set up to do away with privacy and try to get dirt on a person.