I'm not on my PC that has BeerSmith loaded, at the moment, so I can't tell you the exact things you need to set up, but BeerSmith can do it.
From memory--
You have to set up (or choose from the list) what equipment you are using. In the Recipe View, there's a button that's labeled "Choose" next to the Equipment field near the top, and also a "Details" button next to it that you can use to tweak equipment settings.
You also have to choose your mash schedule near the bottom left of the Recipe View. There's a checkbox there that you have to check, to have it adjust the suggested temps for your equipment.
Or, do it the easy way and just put your strike water in your mash tun at about 180F, then wait for it to settle down to the desired temp before you mash in.