Generally, if a USB drive containing an unencrypted file is inserted into a machine running Endpoint Encryption Removable Media Encryption and the user opens the file and saves it, the file is encrypted automatically.
However, if the unencrypted file is opened and modified using Windows Notepad then the file is not encrypted. It remains in an unencrypted state.
Removable Media Encryption only encrypts new files.
When a file is opened and saved by an application such as Microsoft Word, in the background a new file is created and therefore a modified file is encrypted automatically.
Windows Notepad does not create a new file in the background and therefore when the modified file is saved, it stays unencrypted.
Symantec Endpoint Encryption Removable Media Encryption release 11.3 and above.
When editing a file on a USB drive using Windows Notepad, use the File / Save As menu option to save the modified file with a new name. The new file will be encrypted automatically.
Alternatively, open the file using Windows WordPad or a third party editor such as Notepad++ which will result in the file being encrypted automatically when it is saved.