Add www to my url

You’ll have to verify who’s redirecting your domain. Is there any app running there?

If you use python (and requests library) try this

C:\Users\Alexei>python
Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:42:59) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
>>> r = requests.get('http://amdb.com.br')
>>> print r.history
[<Response [301]>]
>>> print r.history[0].headers
{'Content-Length': '178', 'Server': 'nginx', 'Connection': 'keep-alive', 'Location': 'https://www.amdb.com.br/', 'Date': 'Wed, 18 Oct 2017 11:13:34 GMT', 'Content-Type': 'text/html'}

Inspecting all history entries’ headers, you’ll get some hint about who’s redirecting. In this example, nginx itself. I believe your problem isn’t in the DNS, because it doesn’t make redirections. Servers and applications do.

Delete 1st and 3rd entries and add a CNAME value www to server @ (yes, just @)