There is no hosting account attached to your forum account, and there is no account with that domain name that I can find. What was your cPanel username?
There is no hosting account pending, so you'll need to go sign up for a free hosting account. Just log into your account panel https://x10hosting.com/control/login.php, and then follow the links there to sign up for a hosting account. And the nameservers are:
Howdy;
It appears that your hosting account has now been created and should be available for your use.
If you need additional assistance just post back.
Yes. You change it in your account panel. Log in here https://x10hosting.com/control/login.php with your forum username and password. Then click on Hosting at the top and then change your main domain there.
Edit: You should delete your subdomain and addon domain first. Then change your main domain to your preferred domain name.
Backup your files by using the zipping option in the file manager in cPanel. Then download your existing databases using the option in phpmyadmin in cPanel.