OF search is actually quite powerful, with support for regular expressions, but also, I suspect, counterintuitive (and a little clumsy) for many users because its scope is limited by the prevailing focus and filter settings. To search across the whole database you essentially have to begin by clearing the filters and focus, and selecting the library folder in the sidebar.

This is why I personally tend to use saveable searches like:

tasks where (<txt> is in name) or (<txt> is in note)

in Where in OF (for OF 1.8)

(The system will prompt you for the <txt> string)

The advantage of this for me is that it always searches across the whole database, regardless of settings, immediately shows a list of all matches, detects whether any current filters have to be cleared in order to look at anything that has been found, offers to do this automatically, and refocuses down on the relevant set of projects, selecting the matching tasks.

to search only in notes you could use:

tasks where <txt> is in note

and you can keep more complex variants in your search library, e.g.

tasks where (<txt> is in note) AND (<txt2> is in note)

or

tasks where (<txt> is in note) OR (<txt2> is in note)

(for these you would be prompted twice, for two different strings)

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