I have a Ratheon 470 that I use alot for finding structure when fishing or exploring, it works pretty good, especially with bottom contour.
If you are stationary over structure, it will not show shape or form; you must be moving to "see" the bottom detail, but all fish finders are like that.
Also, the transducer angle of acceptance affects how detail is shown.
Can you adjust the sensitivity on your unit?
Screen refresh rate also affects how structure looks on the screen. The faster you are moving, the faster you can set the refresh rate (if you have that option).
Some finders use software to interpret and enhance screen detail, it may or may not be an accurate interpretation.
Remember that, depending on depth and transducer, you might be covering an area that is 20 ft. in diameter, imagine a cone that gets bigger the deeper it gets.
If your sounder is more than 5 years old, you will find the new fish finders to have much better detail.