You can easily flip your exposure to a currency from “long” to “short,” or “short” to “long.” To do this, simply execute an opposing order using margin with more volume than your existing open position(s).
Suppose you have two “short XBT” positions open, at 1 XBT volume each, but you want to close these positions and go “long XBT,” at 1 XBT volume, on 3x leverage. You can do this by buying 3 XBT using margin, with 3x leverage.