Everyone has very private and confidential texts on their computer. Logically, given the nature of these texts, you don't want them to be read by other users. What you need is a free tool like DSE.
DSE is a utility that will allow you to encrypt and decrypt such private documents. The most remarkable thing is the great simplicity of its handling, it does not even require installation. Simply select the text to be encrypted, enter a password and it will automatically be encrypted. This will be totally illegible for any user who does not know the password.
For programmers it is of interest that on the author's website you have the source code (in C) of how this program is made.
You can free download DSE and safe install the latest trial or new full version for Windows 10 (x32, 64 bit, 86) from the official site.
Devices: Desktop PC, Laptop (ASUS, HP, DELL, Acer, Lenovo, MSI), Ultrabook
OS: Professional, Enterprise, Education, Home Edition, versions: 1507, 1511, 1607, 1703, 1709, 1803, 1809