Changing dictionaries in preferences

Hello,

I need some help! I use Adobe Acrobat 9 Version 9.4.5. I am editing a doument in Spanish and cannot get the spell check dictionary to change from English to Spanish. I go to Edit, then preferences, then spelling and I uncheck English and check Spanish. It allows me to change it, but when I go back to the document all of the spelling suggestions are in English. Then when I go back to preferences, the English is checked again as my dictionary.

Please somebody help!!!

Thank you!