If your computer is on a network that utilises a proxy server in order to get online, you may have noticed that there is no obvious way in Internet Explorer 6 to change the username and password that are utilised for the proxy server in the event that your network credentials change. This is because your login information for the proxy server is saved by Windows XP itself rather than Internet Explorer. Use the password manager included with Windows XP to change your username and password for a proxy server.
Click the "Start" button, then click "Control Panel."
Double-click "User Accounts." If you do not see this icon, click the "Switch to Classic View" link on the left side of the screen.
Click the icon representing your Windows username.
Click the "Manage my network passwords" link in the upper-left corner of the screen, under "Related Tasks."
Click the proxy server for which you need to change the username and password, and click "Properties."
Enter your new proxy server username and password, then click "OK" in each open window and restart your computer.