Trading Modify Stop Loss Order on MT4

First choose the open trade you want to modify the Stop-Loss Order for.

Once you select open trade - choose the modify order button and the following trade order popup window will appear and you as a trader can use this trade order popup window to modify the Stop Loss Order Area for your new trade.

This pop up includes settings for setting Stop Loss Order Level - type in your new SL stop loss level & Click the "Modify" button to modify the Stop Loss Order to your open trade.

Trading Modify Stop Loss Order in MetaTrader 4?