Most sound-equipped scale locomotives come with factory settings. That does mean loud. The first thing I do is to change the address (they are all "03" from the factory) to the number on the cab. Then I enter Ops Mode (or also called, "programming on the main"), and reduce the sound level to half of the setting permitted in the "Master Volume" CV. From there I tailor the individual sounds to my preference, and sometimes fiddle with the chuff rate to ensure the synch between the rods cycling and the four chuffs per driver revolution.
Just a hint for future reference: this won't be your last locomotive. As soon as you have a second, and then others, the sound will drive you bonkers. They all compete with each other for your attention because none of them is more than 10 feet away from you on most layouts. If sound scaled, it would be fine, but it doesn't. Like water flowing on a layout, it moves much too fast, and for sound, it's much too loud for the real scale distance your ears and eyes are from the locomotive as you tower over it...or them. That is why most of us learn to reduce the master volume by at least 50% right off the bat...from whatever the factory defaults are. I tend to go even lower, and my bell, hisses, blow-downs, injectors, and pop-offs that take place on most decoders randomly, are usually set near 25% because they are repeatedly endlessly, often, and annoyingly. The bell because, at the apparent distance, I'd barely be able to hear it.
It's your responsibility to figure out how to get the most enjoyment from the hobby, and fiddling with all CV's that the operator can modify (some econo decoders, such as the one likely to be in your Bachmann steamer) have minimal operator control), is a must during that taking on of responsibility. If you undertake it early and fiddle, it will become second nature quickly. If you screw something up, just perform a factory default reset, often CV8 to a value of "08". Never forget to cycle the power after you perform the reset. Shut off power to the rails and then restore it, and your reset will be solid.
I do still think that you are about 99% likely to get at least one other DCC/sound locomotive, though, probably within six months to a year, and when both of them compete for the listening universe within about six feet of each other, you'll probably find that you have found your limit...or you'll start reducing their volumes even more. That's where I like the QSI's with their tunable mute function.
