STEP 1 : Login to cPanel ( Guide here )

STEP 2 : Navigate to Domains -> Zone Editor

STEP 3 : Click on Manage beside the domain you wish to add the TXT record

Fill up the valid zone name and text value according to your custom TXT Record an. If the provider says @ , or you are unsure what to put in the Valid zone name field, fill up the valid zone name with yourdomain.com ( Substitute yourdomain.com with yourdomain )

Click on Add Record after you are done

Please allow up to 24 hours for the DNS to propogate. Please contact support if you have further questions, either by live chat or ticket support