When you use a public PC you should limit your browsing of password-protected sites as much as possible. If you must access a password-protected account, your goal should be to leave no trace of your activity on the PC. In order to do this, right click on the browser icon and open the browser using a setting called Private Browsing or Incognito Mode. This will prevent the browser from storing information about your activity. In addition, go ahead and delete the history and temporary Internet files including all cookies before you log off. Check out this article for more tips on staying safe on a public PC.