I'm glad you asked...because I had no idea I was doing that! I'm still pretty new to the gear. I do not want to see a double echo. I'll dig around in the settings and see if I can change it. Thanks!
The "Lower Depth" menu choice is in the Xpress menu (1 Menu button press) ...
*Auto will keep the bottom on the screen ...
*Manual can be used to make more efficient use of the display vertical resolution ...
*Manual can also be used to see the "double echo" ...like in your image ...
Some guys like seeing the "double echo" ...a strong "double echo" (like your image) is indication of harder bottom ... Allowing the sound pulse to effectively reflect off the bottom ... Then reflect off the water surface ... Then reflect off the bottom a second time ... And then received by the xducer ...
Rickie