If you have a registered a domain name with us or transferred a domain name to us, you can update the domain's Nameservers through your Client Area.
Login to your Client Area here:
https://my.so53.co.uk/login
Then go to Domains > My Domains, click on the 'Manage Domain' button for the domain you wish to manage. On the next page you will seem some tabs, click on the "Nameservers" tab and update the required fields accordingly. You will see that you can have to up to 5 Nameservers for a domain. However, you do not need to complete all 5 fields. If you have only been given 2 Nameservers to use (which is the norm), then complete 'Nameserver 1' and 'Nameserver 2' fields only and remove, if they exist, 'Nameserver 3', 'Nameserver 4' and 'Nameserver 5' etc.
Then click the 'Change Nameservers' button.
See also our article on 'What Nameservers should I use?'