May I ask if “Cloud account” should be “Cloudflare account”,or rather your “cloud account” at your domain registrar interface?
I ask because some domain regisrars require from us to enter the nameserver IPs alongside the domain nameservers. Some do, others not, however maybe that’s not the case for you.
If yes, then you can find your assigned Cloudflare nameserver IP addresses as follows at the article below:
Nevertheless, as @Cyb3r-Jak3 stated, you don’t have to update anything by default. Cloudflare changes and updates them from time to time, if so. No further action required as I remember. The names of the assigned domain nameserver’s for your Cloudflare account doesn’t change. Each CF account has got it’s own pair.
Except, you’re using some other feature maybe? 
Are you an Enterprise customer?