Go login to your account panel.
https://x10hosting.com/control/login.php After you've logged in, click on hosting details, and you'll find your cpanel username listed there. Your password should be the same as the one you login with to your account panel and forum account. If it doesn't work, then you can reset or change your password in your account panel. It'll reset the password for your account panel, cPanel, and forum account all at once.