Starting with a new Windows 11 version, released in 2023, you have a local account on your system and and a permisive one. The later is your name as a user of Microsoft, while the former consists in the first five letters of your name. Jupyter Notebook and an IDE for a programming language can open only files saved in a folder created by the "permissive" account, outside the folders Documents, Desktop, that are under the control of the local account. Hence I created a new folder, Working, and automatically it has been considered as created by the account with my entire name, and I have access to any ipynb file and can save new ones there.