How can I change DNS Cloudflare nameservers
Cloudflare assigns you two Name Servers, as shown in the Cloudflare Dashboard DNS tab. You need to go to your domain registrar and update them there.
that is, where did I buy the domain? if yes, then I changed there but here they are shown old
How long ago? Propagation needs some time and can take up to 48 hours.
What’s the domain?
If Cloudflare is your registrar, how do you make changes so it points to your hosting company?
You can’t point the nameservers to your hosting company. Therefore you either need to configure DNS records on the Cloudflare dashboard, or transfer the domain to a registrar of your choice.