Trades made in Forex mode are not limited by time. That means you decide when to close your trades.
There are two ways to close your trade. You can decide ahead of time and set a Take Profit and a Stop Loss, which automatically close a trade at the levels you set. If you set one or both of these levels, you won’t need to watch the chart. The second way is to close your trade manually, which you can do anytime you want.
Note that an unsuccessful trade will be closed automatically if a Stop Out is reached. The Stop Out for a trade is equivalent to a percentage of the trade amount. If that amount has been lost while the trade is active, a Stop Out is triggered, closing the trade automatically. The maximum Stop Out for a trade is the same amount as what you invested to open the trade, so your loss can never exceed your trade amount.
Finally, if you decide to keep a trade open after the end of a trading day, an overnight fee will be applied to carry the trade onto the next trading day.