First, make sure you have the appropriate file handlers installed for the file type you want to search. We have links to the file handlers for some common file types here: https://www.fileseek.ca/FAQ/#filehandlers
On the Search tab, enter the folder that you want to search in the "Path" text box. Type the file extensions you want to search in the "Include Files" text box (e.g. *.xlsx). Type the text you want to search for within the files, into the Query text box.
Search Tab
On the Advanced tab, disable all of the "Show files/folders..." options except for the "Show file names that match the 'include files' filter" option. Also make sure that the "Process file contents using File Handlers" option is enabled.
Advanced Tab
Click Search, and you should get the results you're looking for!