I have transferred my domain to you. Do I have to modify again NS / DNS settings?
A domain is transferred in IP.GR along with its Registry information. This means that any information stored in the Registry for this domain, will be still active, once the transfer is completed. Thus, if you wish for your domain to maintain the same name servers or the same DNS settings you simply have to do nothing.
On the other hand, if you want to need to change your domain's name servers, you may follow the relevant instructions.Chan
If you wish to modify your domain's DNS settings after being transferred in IP.GR, you will find detailed instructions here.