Rated 4 out of 5 stars

le Gustrónico ar MFómh. 13, 2011 ·

In the "more" page it appears an image with some options, ie: Detect dictionary as I type, Auto-detec locales and Remember dictionary for current site. It took me a couple of days to find them at last:
Right click on the Dictionary Switcher button that you previously added to add-on bar (see MarkaPola comment)

Léirmheas ar leagan níos sine den bhreiseán seo (1.3.1.1-signed.1-signed).