How Search works in the main view:

Typing inside the search box dynamically searches in the notes' titles, narrowing down the list below.



To search in notes' contents, just type the search string (the titles list may become empty, it doesn't matter), then type "Enter". A list of notes containing the search string will appear.



Emptying the search box, either with the keyboard or with the icon on the right, brings back the entire list.