Thanks ~Z~ Man!

It's now working!

First of all:
Before and while applying any changes, disable the Cache from your Ossn administrator backend. Otherwise the old settings/appearance will be kept

Next:
I recommend to use the Custom String component for changes like that instead of altering Ossn core files because otherwise your changes will be lost with every new Ossn update. See

https://www.opensource-socialnetwork.org/component/view/1942/custom-strings

Hey Johannes.

Thanks for your reply. I mean I changed the text like that in bold lines bellow:

'home:top:heading' => "Preparado para a revolução? Bem vindo a versão BETA de %s! A nova Rede Social Educacional - 100% Brasileira - idealizada por professores, para professores! Cadastre-se agora mesmo para trocar experiências, fazer amigos, criar grupos, adicionar fotos, e muito mais!."
'create:account' => 'Criar uma conta',
'its:free' => "É grátis e sempre será.",

Do you mean that you changed something in ossn.pt.php file, or do you mean that you chose Portuguese as your default language and it didn't work?

If you didn't do the second, you can chose your default language to Portuguese in Basic settings in the Administration panel. Then you should be able to edit ossn.pt.php freely.