Asinben

I used to be able to view excel spreadsheets simply by selecting them in Evernote. Now it says "Can't open this document" with a note under that saying "This file isn't available offline. Make file "Available offline" in the files' options menu." How do I make the file available offline? Why do the files not open directly anymore? Do I need another app installed on my phone to view the excel files? This also happens with word documents.