Trailing Stop Loss

 
How do you know if the trailing stop loss is active? 
 

I assume you mean the terminal's built-in TSL. The same way you enabled it; Order/SL/TP Line → Right Click → Trailing Stop (t) → Look at the unchecked None. You can also look in the Trade Tab; orders with a TSL active have the SL highlighted in yellow.

Trailing Stop

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