OneNote

OneNote search only indexes password-protected sections while actively unlocked — a deliberate design choice, not a setting. Encrypted sections sit outside the search index until you authenticate, protecting them even from someone with file-system access. There is no native one-master-password option, but you can get close. The most practical approach is adjusting the lock timeout. Go to File → Options → Advanced, scroll to "Passwords", and set "Lock password protected sections after I have not worked in them for the following amount of time" to the maximum (one day). Keep "Lock password protected sections as soon as I navigate away from them" UNCHECKED — otherwise each section re-locks the moment you browse elsewhere, defeating cross-section search. For the one-time unlock workflow: at session start, right-click each protected section and choose "Unlock This Section" (or Ctrl+Alt+L while selected). Once unlocked, search will include them for the full timeout period. Takes 30 seconds upfront, gives full-search behavior the rest of the day. If you need this regularly, reconsider whether every protected section truly needs protection. Many users over-protect — moving non-sensitive pages out of locked sections dramatically reduces friction. For genuinely sensitive content, the per-section design is protecting you from exactly the shortcut you are seeking: one master password unlocking everything means one compromise exposes everything. A limitation: OneNote for Windows 10 and mobile apps handle encrypted sections differently from OneNote desktop (Microsoft 365). The desktop version has the most complete unlock-and-search behavior. Switching to the desktop client gives smoother multi-section search once everything is unlocked.

OneNote search is designed to index all open notebooks, but password protection introduces a fundamental cryptographic barrier. Because protected sections are encrypted using AES, the search indexer cannot read or index the content while the section is locked. Consequently, it is technically impossible to search locked sections without first decrypting them. To ensure your search results are comprehensive, you must use the global search shortcut, Ctrl+E, which expands the scope across all open notebooks rather than just the current section or notebook. Regarding the password, OneNote does not support a single master password to unlock all protected content simultaneously. Passwords are applied at the section level, not the notebook level. To include this content in your search, you must manually unlock every protected section at the start of your session. Once a section is unlocked, it remains decrypted in the application's memory until you manually lock it again or close the program, allowing the search function to access the text. If you find the repeated password entry tedious, the most feasible architectural change is to consolidate all sensitive information into a single password-protected section rather than multiple protected sections. This reduces your requirement to a single password entry per session. Alternatively, if you use a third-party password manager to store a consistent password across all sections, the friction is reduced, though the manual step of opening each section remains mandatory due to how OneNote handles section-level encryption.

OneNote does not index or search password-protected pages or notebooks by design. The application only adds content to its search index after the protected area has been unlocked and remains open in the client. Consequently, there is no built‑in setting to force a one‑time password entry that automatically enables cross‑notebook indexing. To maximize search coverage, open every password‑protected notebook and leave it in the background so the local index continues to process its contents. Avoid closing these notebooks entirely, as indexing pauses and may drop the protected content from the cache. On Windows, verify that OneNote is included in your system search settings by navigating to Settings, Search, and Search Windows, then ensuring OneNote is enabled. Clearing the OneNote index via the OneNote Options dialog under the Search tab and allowing it to rebuild can also force the application to re‑scan all currently open sections. Note that Microsoft has never implemented true background indexing of locked content, so any workaround will require keeping the protected notebooks open and authenticated during your search sessions. If you require comprehensive, password‑protected content search, consider exporting or migrating sensitive data to a dedicated document management system with native cryptographic indexing rather than relying on OneNote’s consumer‑grade search architecture.