There is an old Internet
expression for this -- RTFM.
You will need to find (or download) the manual for your particular unit and see whether it is switchable or not. Some of them are, and some of them aren't. If it is not switchable, then you will have to change it.
But I'm surprised you would need to -- did you throw out all your AC gear
just because you arrived in the States? The beauty of supplying your AC power on board with an inverter is that you can use whatever power you can find to charge your batts, then feed your AC equipment
with the same nice 230v or whatever power just like you have back home.
chargers I have seen will accept any kind of power (some of them need to have jumpers switched over). And if your battery charger
won't take a different voltage, you can buy an isolation transformer which will convert the voltage (but N.B. not the frequency) for you -- i.e., step up 110v power to 230v so that your battery charger
can use it.