Acura 2009 TSX Owner's Manual page 146

Seats
Armrest
Front
LEVER
To use the console lid as an armrest,
slide it to the desired position while
pulling up the release lever. Release
the lever to lock it in position where
you want it to stop.
140
Rear
The rear seat armrest is in the
center of the rear seat. Pivot it down
to use it.
A beverage holder is located in the
armrest.