Translation settings

Go to System → Settings → Store Details

Auto-translate Status

This enables copy or translation of missing text definitions or language-specific data if text values are missing for used language.

Source language for translation

Select source language to be used for auto-translation. Will work only if you save translatable content in selected source language only. If you change texts in any other language, a translation will not be happening.

Text Translation Method

Select the method you want to use for translation. The default method is a straight copy of source language text also other methods can be available if any translation extensions installed. For example Google translate extension use Google Translate API v2 to translate from the source language to all other available. 

Override if source language text was changed

If enabled, text in all languages will be replaced with the new translation in case source language text was edited. For example, if your source language set to English and you edit a product (or category) then product name, description, the blurb will be copied/translated to all others enabled languages