Outlook 2011 for Mac – search function only searches text of emails and not attachments

I have had previous versions of Microsoft Outlook for Dell computers. The past few versions have all had a feature that has become essential for me. When using the general search function, if I typed in a few words it scanned text in the body of the emails, but also in attachments such as Excel, Word and PDF.

I have not been able to figure out how to do this on my 2011 for Mac. When I type in some words to search it only scans the body of the email and not any attachments. This is very difficult to use as is for my business. 

Is there some sort of setting I need to change to make the search function more robust? I tried adding Excel, Word and Adobe in Spotlight Privacy and then removing them to re-index, but that did not work. 

Thank you and I look forward to hearing from you.