There are two ways to set the security bit on the Quartus II.

1. Select the "Enable Security bit support" option in the Device and Pin Options tab.
For details, refer to the document "Quartus II Getting Started Guide - How to Set Device and Pin Options".

2. Select Security Bits in the Quartus II Programmer.
Refer to the Quartus II Getting Started Guide - How to Program Devices document for more information.

When you submit the generated POF file to the Quartus II Programmer after turning on the project security bit in the Device and Pin option, the security bit Box is automatically checked.
(It is also possible to write by removing the check on the Quartus II Programmer.)