How to set a password for the PLC program,What is the difference of triple password protection?

Set password modification in the program menu bar file [program project properties],it means that the file can't open

Modify the password in the program menu bar PLC [PLC password],it means that PLC forbids downloading.

Set and modify the password in the PLC main program block or sub-program block (right click on the program properties)

Download the program,tick "forbid upload",it means that the program can not be uploaded to PC.