Flint,
- Once you set your contrast, it should generally stay set for the given water conditions. If you're like me and having trouble seeing the screen in the sun, go to Walmart and buy a static cling screen protector (EVERYONE should do this regardless) and apply that. It helps. Also try using the white background. Or black and white so there is more contrast that can be seen in the bright sun. I use white background because I can see it best. To each his own but that may help.
- Turn your depth range to auto
- If you are zooming in, it will zoom into the bottom on auto. If you want to zoom into a specific range, set your depth range to that range plus 5-10ft and you can then zoom in to say 30ft range. Make sense? Keep it on auto and it won't loose bottom
- The alarm "crossed GPS something" sounds like it can be turned off under the "chart" menu. Try page 37 of the menu

You can download the menu here