The English I am struggling with is not British English, and I can't seem to be able to opt for British spellings etc.

No instructions for proper installation

Il me plait car c'est l'anglais que je comprends le mieux.

Não funciona

Would be amazing I'm sure if only it opened in Firefox. Despite my best efforts the default remains the despicable English (US)

You can install it, but the langauge is not selecteble.