My Xbox Live account is in Spanish. Presumably because I purchased an Xbox Live Gold subscription in Spain along with my Xbox. I wanted to change this to English because I would like to have Xbox Live content delivered to me in English (e.g. game trailers, XBLA games, movies, etc), and also because I plan on leaving Spain and want to purchase future XBL timecards through Amazon.co.uk (an additional benefit is that those are about €10 cheaper than the ones in shops here).
Because it took me three days to get an answer from support and this information is absolutely nowhere to be found on the Xbox Live support pages, I figured I would post it here for the Googles to index (relevant parts highlighted, tl;dr: delete account, lose GamerTag, friends, purchases, achievements):
Hello Cris, Thank you for contacting Microsoft online support for XBOX. I am Billy and I appreciate the opportunity to be of help.
I understand that you want to set or to change the default language on Xbox Live and you have some questions regarding regional differences on your Xbox Live subscription codes.
I appreciate you taking the time to write us with your concerns and I am glad to have you as a valued customer.
Cris, you cannot change the country or region of an Xbox LIVE account once you create an account. However, you can select a different language if more than one is available. If your preferred country has no other option aside from the default language, I regret to inform you that you will have no option to change the language on Xbox Live. However, if you are currently located in a country or region that is different from your account’s country information, it is advisable to cancel the account and create a new account using your preferred country of residence. This will ensure all information is correct and you will enjoy all the Xbox LIVE features for your preferred country. Please be reminded though to use a billing address for your account that is among the list of countries where the LIVE service is supported. If your preferred country of residence is not on the list, please check back with us soon-we expand our services frequently and may be coming to your country in the near future.
Note: To change your personal data on your Xbox LIVE membership, kindly go to the Xbox 360 Dashboard and select Account Management. You can also make changes online at https://account.live.com. Please make sure your Windows Live ID is correct before proceeding. You can also verify this information at www.passport.net.
With regards to your second question, a pre-paid code is the generic term for the 25-digit sequence of letters and numbers that a customer enters in the console dashboard to obtain a variety of Xbox LIVE offers. It may be obtained in a starter kit or in a stand-alone package, for subscriptions of various lengths and different MS Points denominations. There are also free codes that you do not have to pay for. Examples include game codes found in bundles, downloadable content codes found in certain games, and 48-hour trial codes, each of which unlock content or time on the service yet do not cost anything.
Please be informed that the Xbox Live subscription codes are region coded. We do not recommend that you try to use an Xbox Live subscription codes in a region for which it was not designed for use. In this regard, you will be unable to use the subscription code to a different region.
For updates, please visit our website at www.xbox.com.
Thank you for your time and understanding. It has been a pleasure to assist you.
Confirmed this on Twitter with @xboxsupport, who do seem to be native English-speakers:
@HerperDerper Unfortunately, yeah. Accounts are region specific (often times for legal reasons due to the regions laws regarding content)^MK
The region-coded licensing thing was obvious, but it seems such a silly excuse. Delivering Spain-licensed content to another country is apparently fine if you move (because you can’t change countries in XBL). And somehow Schengen, Europe, and region 2 don’t seem to apply to the Internet.
