Dont you think your Notepad files are not secured because you dont have any password facility and the files can be accessed by anyone? Its time you can make a simple text file secured with all your confidential data within it encrypted and a software which does this possible would decrypt the file when required.
Check out LockNote – a small application which is a tool for hiding your important data which you save in text files. The best part of using notepad file locker is that you dont need to install the software and it can be used from a pen drive too because to directly use feature. You can instantly drag & drop the files and encrypt them for the highest security and decrypt them when you want to use them.
You just need to Copy paste all the data of your notepad file into this applications text editor and close it, to save and enter a password. Next time when you try to open the LockNote application you are asked to enter your secured password, and once you enter it you are given access to the contents of your encrypted notepad file.