If you are in a catalog or playlist folder, you can search within that catalog or playlist folder only by typing text into the search bar.
If you'd like to use advanced search options, click the More search options icon in the search bar.
The advanced options for the tabs in your catalog have different options.
Song advanced options
Recordings advanced options
Files advanced options
Another feature of the advanced search options is the option to change your search from searching the current playlist only to searching your entire catalog. Click the Search everywhere icon in the bottom left of the advanced search options modal to apply your search to the entire catalog.