Change language region

[persep]

Hi
I changed in "System Preferences -> International -> Formats -> Region" my original region of Spain(English) to Spanish(Spain) but that changed the date language,now it comes up in spanish and I want it back in english. The problem is that in the region list, even with the show all option, there isn't the original spain(spanish), I can't find it anywhere.
The funny thing is that originally the region is country(language) and now all the possible options are language(spain).

Please how can I get it back?
Thanks

 

[persep]

Update

If I make a new user, this new user does have the correct region setting spain(english)
But I don't know why?

 

[YS2003]

Talking about the language setting, I would like to know if Mac OS X is basically same internationally as it comes with variety of languages pre-loaded in the OS X. For example, is the difference in OS is basically the default language setting depending on where you buy your Mac? This question does not include the power plug and keyboards as they are localized for each country where Macs are sold.