X515C DF & X510C Manual - Lowrance

Screen Command (left). Screen Menu with Contrast bar selected (right).
To adjust the display's brightness:
Press ↓ to BRIGHTNESS. Press → or ← to move the bar. The left end of the
scale is minimum contrast; the right end is maximum contrast.
To adjust the screen's display mode:
Press ↓ to DISPLAY MODE|ENT|press ↑ or ↓ to select mode|EXIT.
Display Mode menu.
Sensitivity & Auto Sensitivity
The sensitivity controls the ability of the unit to pick up echoes. Sensitivity
can be adjusted, because water conditions vary greatly. A low
sensitivity level (from zero to 50 percent) excludes much of the bottom
information, fish signals, and other target information.
High sensitivity levels let you see this detail, but it can also clutter the
screen with many undesired signals.
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