For the definition of Take-Profit and Stop-Loss limits, see this article: [Margin] Take-Profit and Stop-Loss
Find the trade you want to edit in Positions panel. You will see two small indicators, TP (Take-Profit) and SL (Stop-Loss) surrounding the market price of the trade.
In this example, as we are editing a long trade, we will set TP at $4,500.00 and SL at $3,800.00.
Click on the TP pencil button.
Input 4500, then click the check symbol to save. System will ask you to confirm the number. Click Yes to continue, or No to edit the number.
TP limit has been set. Follow the same process for the SL limit.
This trade will now be executed when market bid hits either $4,500.00 or $3,800.00.