Heath Motion Sensor How May I Adjust The Sensitivity Of Motion Sensor Light?

How may I adjust the sensitivity of motion sensor light? - heath motion sensor

I bought a Heath / Zenith Motion Sensor Light Model SL 5412, which was installed by a professional. There seems no apparent reason, and apply often. It was a few weeks after installation, but in recent days has on several occasions. Some sites have tried to point out that the sensitivity can be adjusted, but I can not find buttons or something like that would be less sensitive. Any help in this regard is greatly appreciated. Thank you.