Trailing Stop works only on the desktop MT4 Platform.
To set a trailing stop:
1- Right-click on your open position
2- Choose ‘Trailing Stop’
3- Select the number of ticks distance to the current market price from the list, or specify one from the Custom button.
4- The Trailing Stop order will be activated when the order moves in a profitable direction by the exact number of Ticks set.
Note: If the client terminal is closed, the trailing Stop function stops working because it is not saved on the Server, and only the last present Stop Loss is considered valid.