How to successfully change a virtul server's owners mail address

Hello in one of my virtual servers i’am tryign to change the owners’ smail address from akis@varsa.gr to info@varsa.gr

So i clicked on edit viirtula server can i chnage the mailbox name suffix to info and the contact mail to info@varsa.gr and set a password.

No matter how many tried i make, i get login failed in thunderbird.

Please help me change successfully the owners mail address