Fedora :: Having Es_ES Language And 12 Hours Format On Clock?

I noticed that the language es_ES (Spanish Spain), has a problem, you can't put the clock in 12 hours format, I was googling for a while and found that it should edit the file

Code:

/usr/share/i18n/locales/es_ES

Find these lines

Code:

am_pm "";""
t_fmt_ampm ""

and replace with

Code:

am_pm "<U0041><U004D>";"<U0050><U004D>"
t_fmt_ampm "<U0025><U0049><U003A><U0025><U004D><U003A><U0025><U0053>/
<U0020><U0025><U0070>"

But I did it and still don't show me the option to change the clock to 12 hour format, I tried changing the es_NI language (Spanish Nicaragua) and gives me the option of 12 hours, but the languages ​​of programs like firefox, thunderbird, openoffice change to English.What can i do to have language es_ES and 12 hours format on my clock? or es_NI language with firefox, thunderbird etc. in spanish?