Dell S520 Guide D'installation page 12

Set Up Laser Touch on Your Projector
Part G: Touch Sensitivity
Adjust
When laser curtain has been operative for a
long period of time, the sensitivity might be
slightly reduced. Touch sensitivity functions to
re-sensitize the laser curtain by restoring the
initial setting.
Executing driver, click the
Advanced Settings menu, click the Set touch
Sensitivity option to re-sensitize laser curtain
by restoring the initial setting.
10
icon, and go to
Default value for Touch Sensitivity is 4.
Increasing the value increases the Touch
Sensitivity and Decreasing the Touch Sensitivity
values reduces it.