If you are using the default nameserver, then you can change the nameserver from the domain management section from the client area, but if you have pointed your domain to a cPanel server using nameserver (in most cases) then you can change your DNS settings from cPanel. To do that, log in to your cPanel and go to Zone Editor from the “Domains” section.
Click on Manage Button Beside your domain name
From the new page, click on the down arrow beside “Add Record” Button and then Click on “Add TXT Record”
Add a valid zone name or your full domain name on the “Valid Zone Name” box and enter the value that you want to add on the TXT box then click Add Record.
Your DNS TXT record has been successfully added. As the DNS settings can take up to 24 hours to propagate, please wait for that time if you do not see the changes effective immediately.
You can also add other DNS records such as A Record, CNAME Record, etc by following this method.