|I don't know why you are not doing what I think is the logical thing, here is what I would do.|
1: Regional Options, alongside > Customize, on the left hand side, click the button & use the scroll bar to select your option.
2: Go down the bottom of the page to > Location, click the button & select your country.
3: Languages, click on > Details & select your > Default input language.
4: Installed Services, click > Add
5: Last page to open, Language for non-Unicode programs. Select your language.
6: Don't do anything else on that page.
If you don't get the desired result, play around with those settings.