How did you set up your subdomains for your domain? You should have used the Control Panel command to create a subdomain, rather than directly editing the A record. If you didn't use the LPCP or cPanel "create subdomain" function, you should back out all your A record manual changes, and use the function.
Don't forget that any changes made to your domain registration can take up to 72 hours to propagate world-wide and be visible to you. I don't know if A record changes take that long, or immediately show up.