Acidburn: For the trade system it's mandatory that you know if you're in the US or not. If you are no US citizen, you must NOT use the nfa systems - they are for US accounts only. But if you are in the US, you have an US account and can not use other systems but the nfa systems.

Selecting a wrong system might still open trades, but the trades are then not closed correctly. US accounts are not allowed to directly close trades. They must open opposite trades instead.