If I have created a account for 1 of m customers and change the hostingplan or password after, the customer won?t be able 
anymore to login with ftp anymore using ftp@domainname.com and the password used for this account. The only way to access with a ftp programm is creating a extra ftp account in siteworx
I just want to make sure I understand the problem. You created a siteworx account (for example, domain.com) with password ‘mypassword’ (again an example). The master ftp user account ftp@domain.com was created with the password ‘mypassword’. Then, you changed the siteworx login password to ‘newpassword’. Now, when you try to login as ftp@domain.com, the password ‘mypassword’ no longer works?
If you didn’t know, the siteworx login password and master ftp password are stored in separate places and are actually different. For convenience, when the siteworx account is created, the master ftp password is set to the same as the siteworx login password. But, after the siteworx account is created, changing one will not change the other.
[SIZE=2]Yes, I think you understand it right. If I change the password of a siteworx account, the original password for the ftp doens´t work anymore. The same thing happens if I change the hosting plan for a account. For example, domain.com had first 50 mb and 1 Gb traffic, I change it into 100 mb and 2 Gb and after this I can´t enter my master FTP anymore.[/SIZE]
If you could please open a ticket, we can check it out and figure out what the problem is. 
Thanks,
Socheat
[SIZE=2]I created a account type for domains wich are just parked for a while. In this pre-defined account template I put the ftp account on 0. I don´t know if this can be the problem because when the account will created there won´t be created a main account. I don´t know what happens if this account will be upgraded to another package after, will the main account still be created?[/SIZE]
[SIZE=2] I am checking this now to see if this was the reason. Let you know more soon.[/SIZE]