If you are using Cloudflare nameservers, you manage your DNS at Cloudflare and that means you may have to update your A record at Cloudflare from time to time.
This guide shows you how.
Login to your Cloudflare dashboard:
Click on the domain name you want to update the A record for from the main page:
Click the DNS button from the top menu:
Locate your domain’s A record (under the Type column), and click the Edit button on the right:
Delete the old IP address and replace it with the new IP address under the IPv4 Address field, and click Save to save changes.
It can take up to 24 hours for the DNS changes to propagate (DNS propagation is the process of updating every server across the internet with new information) globally.
You can use whatsmydns to track the progress of the DNS propagation for your domain.