In Tembo, you can select which folder or volume to search by clicking its name in the main sidebar.
The list of locations can be configured in Tembo > Preferences > Locations. You can also have Tembo search a particular folder by dragging the folder from Finder to the main sidebar.
To search several locations at once, hold the Command key as you click the second and subsequent locations. For example:
- Click Movies in the sidebar to search your Movies folder
- Hold the Command (Apple) key
- Click Pictures in the sidebard
- Tembo will search both the Movies and Pictures folder

Much the same technique can be used to select several filter values after drilling down into a group.