What are you using for lure? I noticed that on my x67c that with a thin profile lure it's harder to pick up. Jigs like spoons etc. need more sensitivity adjusting but that's just my experience. Do you have it in chart mode? Manual settings on, and adjust upper and lower units. What depth are you picking up fish at? Try setting your uppers and lowers to the depth the fishing are coming through at and the sonar will concentrate its signal at that depth.