This really should be easy but I can't figure it out for the life of me.

I work in a multilingual office and sometimes I need to make spreadsheets that have dates in them in Spanish and English. My version of Excel is setup for English, and that is how I generally use it. But now I want to take an existing spreadsheet and change the dates into Spanish. So instead of listing "1-Jan" it should say "1-Enero" or something equivalent.

I tried changing the language for every cell to Spanish, but that didn't do anything.

Any thoughts?

Thanks,
Justin