Hello Poké G,
I’m Gunasekar and I will be happy to help you with your question, I am a Microsoft consumer like you.
Forgetting the password to your password-protected Quick Notes in OneNote 2016 can indeed be a frustrating situation. Unfortunately, if you have exhausted all possible passwords and cannot remember the correct one, there is no official way to recover or bypass the password within OneNote itself.
The password is not stored at any place on the computer or within the application. So, there is no way in which it can be recovered. This feature is specially designed so that even if you lose your computer the data can be secure. The OneNote section password is used (not stored) for encrypting the section. So, you need it again for decryption. This is a really secure solution.
So, if you cannot remember the password, there is no way to recover the files. Unfortunately, Microsoft did not give any recovery option to recover the forgotten password for OneNote notes. However, on the brighter side, you can make unlimited attempts to recover the password and still don’t get locked out of the system for multiple failed attempts at opening the password-protected file.
I hope this information helps. If you have any questions, please let me know and I’ll be glad to assist you further.
Best regards,
Gunasekar N