2005 maxima fold down rear seat

Hi,

I have a 2005 Nissan Maxima SL. 5 passenger. No center Console in
back.

How do lock the fold down rear seat on the passenger side.
When I am driving the car, if make sudden stop, the rear fold down
seat on the passenger side will come down. I don't want this from
happening. The rear seat on passenger side can be easily pulled down.
There is release knob in back, near the rear glass, When I pull up the
door on top of the knob, the knob is inside. If push down this knob,
it will stay down. In other words this release button is always, it
won't lock down.

How do I secure this rear seat fold on passenger side so that the rear
seat does not come down so easily. How do Lock this.

thanks