Sugget you play with the choice of palette colors till you find one that is easy for you to see/interpret. Use just one side for docks, I use the right side since I've got a side console boat. Adjust the screen so you can see the entire right or left side to get better detail. Get a suitable memory card and try different palette colors, speed and settings and record the different passes/settings on the memory card. Then load the pics on your computer and you can study them to find the best setting(s) for you/boat and conditions. Try and leave the settings visible so you can then easily identify which one(s) work the best. Don't ask how I can suggest this tip.
Every day will be different due to water clarity, weather conditions, etc., but once you learn the base settings you can adjust a bit I have a G1 and I can adjust the ping speed in one of the sonar menus but don't know for the Touch models.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.