Please refer below steps if you would like to change nameserver for your domain.
(1) Open your web browser and go to https://ca.myduniahosting.com
(2) Click on Account button on the right hand side of the web menu and login using your credentials.
(3) Once login, you will be prompted with your account dashboard.
4) To manage nameserver for your domain, click on Domains menu and click on My Domains.
(5) You will be then redirected to My Domains page where you will be able to see all the domains that you have bought from myduniahosting.
(6) Choose the respective domain which you want to edit nameserver, then click the drop-down list button and click Manage Nameservers.
(7) You will be then redirected to managing nameservers page. On this page, choose Use custom nameservers (enter below) and fill the Nameserver 1 and Nameserver 2, then click Change Nameservers button.
(8) After finish, you need wait until your domain fully propagate. Normally it will take until 24 hours.