Well, I feel pretty stupid. I discovered why I couldn't get Accu-Fish to work. The sub-menu you get when tapping the sounder screen is actually larger than what is presented on the screen. If you push the sub-menu up, there is an option to turn on/off Accu-Fish. Just posting this in case someone else makes the same mistake.
By the way, I also updated to V5.03. Quick and easy.
By the way, I also updated to V5.03. Quick and easy.