Sorry for posting in an old thread, but I believe it's still relevant. There's another such thread which was closed: Search within folder/notebook
Basically, currently searching within a notebook is not quite convenient. The idea of typing notebook:name prefix is cumbersome when you have to often search only within a notebook.
I do understand that there're many use cases when all notes need to be searched (and I also do this). However, I strongly believe that it needs to be addressed in a different way, which supports both variants.
There's also a usability issue atm: the "Search" field is located among the notes (New note button, notes sorting button, notes list). This suggests very specifically that the search will be done among the list below. However it suddenly does the search across the entire account. The relevant location in this case would be above Notebook list on the left.
So, my suggestion would be one of the following:
Option 1:
Have 2 separate search fields: one above the notebook list on the left - to search all notebooks, like currently; another one above the notes list (like now), but make it search within the current notebook only
Option 2:
Add a tick next to the search box (and remember its state): "Current notebook only". This would make people with both use cases happy. One likes to always search all notes - fine the tick stays off (can even be hidden via custom CSS). One likes to always search current notebook - also fine, the tick is always on.
Option 3: (maybe less preferable, but could be implemented together with the above)
Add a shortcut for the current notebook search. I.e., instead of making the user type "notebook:name" where "name" changes from notebook to notebook, have a static shortcut like "current: " or "here: "