To search your entire database in OmniFocus 3, click the magnifiying glass icon in the search bar and choose Search Everything from the menu. Global search was added to OmniFocus 2 for Mac in version 2.8
Versions of OmniFocus for Mac prior to 2.8 don’t feature global search, but you can still search all of your items by using the built-in Changed perspective. This perspective is already filtered to show tasks of every status in all projects, and terms entered into the search field in this perspective will yield results from your entire database.
If you have Pro, another option is to create a custom perspective. Here’s a screenshot that shows the settings you can use to create an “All” perspective. Searching in this perspective will show results from anywhere in your database.
