How can I change the user interface language?

I am using LibreOffice version 5.1.5.2 in Linux openSUSE Leap 42.1. My system was installed with Portuguese (Brazil) as default language. I have installed also English and Russian as additional languages.

When using LibreOffice the user interface is in English. When I click on the pull down menu in Tools > Options > Language Settings > Language > User interface, the only options are English or Russian and I can not change it to Portuguese (Brazil).

All other language options In the menu (Locale setting, Decimal separator key, Default currency, Date acceptance patterns and Default language for documents) are Portuguese (Brazil).

I have uninstalled and then installed LibreOffice again, but the problem was not solved.

You need to download and install a language pack for the language.
https://wiki.documentfoundation.org/Documentation/Install/Linux#Setting_Up_a_Language_Pack

When I click on the link, get an error message:
502 Bad gateway

Try again. The link works.

When your user account is in English or Russian language: after you’ve installed Libre Office, run the “Language support” tool from the Cinnamon / Mate / Xfce menu. It should report missing translations and it should offer you to install them. Agree to that.

@annwriter - The gratuitous link is simply spam. Don’t. Thank you.

Thanks, it worked!