First things first, with language problems, you must first make sure
that the language in the regional settings on the control panel is set
to the language that you want to use. After you have set this, then
reboot your pc and make sure that word is set to the same language and
also outlook. All programs that use word as the editor should reset to
the language set in the regional settings, but we are dealing with MS
here and we can't take things for granted that they'll work as they
should. If this fails go back to the regional settings and delete the
other language services in the language tab >> details button, to make
sure that the system has only one language service to deal with; lets
not confuse the poor MS OS.

This should sort out your problem. By the way, this solution also sorts
out a problem you might have of not being able to add words to your
custom dictionary or the "add to dictionary button is greyed out" when
you want to add a new word to the dictionary.

Hope this is of use to you.

Lwando Nkukwana
Keep Well