Why is my Adobe Acrobat Pro XI displaying in Spanish..how to revert?

Seems that about six months ago, when I had to reinstall my Adobe Acrobat Pro XI on my desktop due to faulty hard drive replacement - it now boots up in Spanish language.  I've tried all the online recommendations on changing the language to "English".  Which was done successfully, but it STILL is showing up in Spanish.  Furthermore, it's expecting me to register again - as the DC cloud version - and when I use my adobe serial number from my account for the product - it's giving me an INVALID serial number response. 

Help.....it's a great product....love it as is...and I can't use it now.  Please advise on how to address both issues.