I finally found it! I'm so happy I can't believe it. The malware was indeed stored in my internet router. The link below shows what the malware is, show some pics of the ads that are exactly the same as mine were and how to remove it. Below the link I translated everything if you're interested. Thank you for all your help.
"Many people find it weird but it's true that some modems can be infected by a virus or can allow the connection to be directed to other websites or keep showing ads all the time. This occurs because of some vulnerability that modern modems have and because all the modems have the same factory passwords.
These ads and massages can appear when you use your computer, or on smartphones or tablets holding Android, Windows or iOS.
On smartphones the malwares are so so irritant that it's almost impossible to navigate, because ads appear all the time on new tabs asking to download a new app saying that your phone is infected or with low battery and you can't close the window (see some pictures below).
On computers or notebooks the problem is that banners with ads keep appearing nonstpo, usually on the lower right corner and new pages open by themselves. See below.
On my case everything started when NetVirtua (brazilian internet provider) changed my modem to ARRIS model TG862. I thought that my line was infected since all of my notebooks and smartphones had the same issues. Although I started to think the problem was with the modem because when I connected my phone on other networks the ads didn't appear.
But why does this happen?
Since the factory password for modem/router ARRIS is 'password', the virus or malware uses this vulnerability to alter the DNS address on the router and redirects the conection to specific addresses. So when you connect to the internet on any device you see nonstop ads everywhere.
I did a research and found some people with the same issues like in the comments below:
While using Chrome on my phone it says I have a virus and it asks me to download a new app. I was on the street and returned the phone to factory settings and it worked fine. I got home and everything started again. The same happened to my wife's phone."
(pretty much the same)
During the research I found how to solve the problem and it worked just fine. Here's what you should do:
Access the modem configurations using any browser and typing IP 192.168.0.1
Log into you ARRIS modem using the factory login and password:
Go to the "LAN" tab and change the main DNS / secondary DNS to Google's (18.104.22.168 and 22.214.171.124)
Access the "FIREWALL" tab and activate it
Acess the "BASIC" tab and change the modem password.
Reset the router and wait five seconds to turn it on again.
On the smartphone. Disconnect it from the network and clean all browser browsing data. Restart the smartphone.
Do the same with the computer. Disconnect it from the network, go to the configurations of all your browsers and clear the browsing data.
That's it. No more ads for you."