You can use a stop-loss order to limit your losses on both long and short positions.
If the order is used on a long position, a market order to sell is triggered at a pre-defined price – and the order will be filled at the best available price in the market. Please note that execution is not guaranteed.
To set a stop-loss order on your open position, simply right-click on the position line, select Take Profit / Stop Loss from the menu, insert the price and click Place order.
Learn how to place a stop-loss order in this short video.