I ran into the same issue when I borrowed a buddy’s Humminbird a while back. Those devices are great, but the menus aren’t always intuitive if you’re not familiar with them. I ended up finding what I needed on
https://manuals.online/humminbird — they’ve got downloadable manuals for different Humminbird models, old and new. It saved me a lot of frustration on the water because I could quickly look up how to calibrate and adjust the sonar properly. Definitely worth checking out.