One of the best ways to prevent others from using your account is to change your password occasionally—especially if you’ve given it to someone or you suspect that someone might have guessed it or watched you type it. When you change your password, create one that can’t be easily guessed (don’t use "password" or your well-known nickname, for example), and try to incorporate both uppercase and lowercase letters as well as one or two numbers. Of course, don’t make the password so complicated that you can’t remember it!
Click the Start button, and click your account picture to display the User Accounts window for your account.
Click Change Your Password to display the Change Your Password window.
Type the new password again to confirm that you didn’t make a typing error.
Type a hint that will remind you, but no one else, of this password.