You can change your FTP password, but not your login.

A new password can be generated within your Control Panel.

Depending on what account you have with us you may be able to have multiple FTP logins so you can provide others access to part of your site.

You will find all this information within your control panel or you can review the control panel manual. 

http://www.troublecenter.com/index.php?_m=downloads&_a=viewdownload&downloaditemid=1&nav=0