Best find someone that has one or a guide who uses Garmin and hire him. Bass Pro used to offer free electronics classes , might check and see if they still do .
Moderator of Beginners n Mentoring forum
Takeum Jigs
If you don't get the response to help have a moderator move it to Fishing Electronics and Photography there is a sub forum for Side/Down Imaging. I have the same unit and got the interference problem solved in that forum. I also reset every thing back to factory settings after I tried to adjust fine tune mine. Go online and download the Owners manual, it has more info than what come in the box.
You know me, I'm always ready for a road trip. Chip Newest member of Traveling Team Overalls