As JCR TX said he is exactly correct the Legend can be as easy as you want or you can venture into the different settings and make it as difficult as you want (I do not recommend this approach being new), but if you change something you need to think about why you are making that change.
if you do change things you can do a factory reset now in the Legend and take it back to the beginning or to factory settings
The factory settings are pretty much turn on and detect settings, which is where I would start to just get a feel for the Legend, the factory default settings are pretty good to start out with, as you get more acustomed to detecting and the language the Legend is speaking start venturing into making changes, that is really the only way to familiarize yourself with a detector change things and reset to factory defaults when something is not working, the other thing I recommend is to set down with the manual with your Legend booted up and go page by page and just check out what each button does, you do not have to change anything but it gets you started familiarizing yourself with what each button does