Humminbird LCR 120 Operation Manual page 29

Display Speed
8. Setting Display Speed;
Factory Setting: One Level Below Maximum
The LCR 120 display is "updated" (advances across the screen) as you
move through the water. The speed at which the display is updated
depends on the Display Speed setting. To adjust it, select DISPLAY
SPEED, and press the Up arrow button for a faster setting or the Down
arrow for a slower setting.
In general, higher Display Speed settings provide faster updates,
while slower Display Speeds provide more detailed information.
Depth Range
9. Setting Depth Range
Factory Setting: ON (Automatic)
When you turn the LCR 120 on, it finds the bottom \, sets the ideal Depth
Range, and automatically adjusts the Depth Range (to as much as 120')