Al, when you have an open position (trade has executed), you should then have a yellow T chevron on the top right of your chart. If you drag that down & let go it will open up the Trade Manager with the default Below Price or Above Price Stop selected. If you were to click Submit at that point, it would add that stop to your existing trade. Instead of clicking Submit, change the stop from Below/Above Price Stop to the trailing stop that you want by selecting it in the stop list. Set the parameters you want for that stop, then click Submit. That should work, but there may be certain option trade configurations that may not.