How to change NS addresses?
1. Log in to your personal account https://billur.com
2. Go to Domains -> My Domains
3. Select the domain you need and select the action "Manage name servers"
4. In the Nameserver fields, enter your NS address
You can specify a maximum of 5 NS addresses; for correct operation it is enough to specify 2 NS addresses
5. Click the Change server name button