If you changed your name server to Cloucbric’s name server, then you need to add FTP record. Go to your DNS page in Settings - Name server and update your FTP record. It should remain as your original IP address. Don't forget to save changes.
But if you changed your A record & CNAME, then you need to modify your FTP record on your domain hosting provider's DNS management page. You should set your FTP record to your original IP address.
If you need help, please submit a ticket through https://cloudbric.zendesk.com/hc/en-us/requests/new.