You can never go wrong with the preset settings and the Trac in Ground. You will find the Disc preset of about 3 will disc out a lot of trash, but you will still see VDI's in the single digits where you may expect to find small gold items. The preset gain of about 9 will give maximum gain with the minimum amount of chatter.
Experiment with the Coin & Jewelry mode and Relic mode. It seems each of us have developed our own preference to one of these modes, but each program does very well. Some prefer the single tone of the C&J program and they learn differences in the tones to determine the probability of a good target. Others prefer the two tones of the Relic program, where any target above the Disc setting is a high tone, anything below the Disc setting is a low tone, and anything the machine isn't really sure of is a kind of 'honk'.
There isn't a lot you can change on the MXT's setting, but there is a learning curve to the MXT, just like any other machine. Essentially if you set up your machine on the presets and dig all good, repeatable targets you will be finding some interesting things. As you learn the machine you can experiment more. I would also suggest re-reading the manual and review the tape if you have it.