Some site will have IP detection to redirect to the correct language for that IP address.
I don't know if that is the case here.
If you are in Brazil and using a USA VPN IP address, Yahoo could probably still identify the country of origin and redirect the br.yahoo.com site.
Are you, using the same IP address to connect to the Avast Forum (if so this could be related to the details given on an IP search) ?
Are you actually in the USA, if so why would you need to use a VPN to connect ?