First, you should know that it is illegal to change someone else's address without their consent. If you consistently receive mail at your address for someone else, then the best thing for you to do is visit your local post office. Let them know about the situation, and give them the names of everyone who should be receiving mail at your address. They can attempt to find the correct address for the previous resident so that their mail is properly forwarded to the new address. In addition, be sure to write "NOT AT THIS ADDRESS" on all mail received for that particular person. The amount of mail that you receive for them should begin to diminish as people learn that they no longer live there.