You need to make DNS adjustments for your new hosting accounts using a template at WHM.
For this:
1- Login to Cpanel.
2- Manage the DNS templates with Edit Zone Templates.
3- Change the NS records to your own DNS server names.

Note: You can also enter other generic records to be used in new hostings like SRV, TXT etc.

This template will be used for all new hostings you kreate.
For existing hostings use Reset a DNS Zone to correct the DNS records.