There are two general types of Margin trading in crypto-markets - Isolated and Cross Margin. The Margin Trading at Changelly PRO uses the Isolated Margin. 

Isolated Margin mode allows traders to manage their risk on certain positions by restricting the amount of margin set for each position. The margin balance for each position can be adjusted.

If a trader’s position is liquidated in Isolated Margin mode, instead of their entire margin balance, only the Isolated Margin balance gets liquidated. The Isolated Margin amount can be adjusted for open trades. If a trade in Isolated Margin mode is to be liquidated soon, it can be prevented by adding extra margin to the position.

For instance, if a trader opens a long margin trade on BTC-ETH market with a margin amount of 1 BTC and the 2x leverage, their total order value is 2 BTC and the amount they're risking is 1 BTC. It also means that in case of the BTC price going down the order will still be open until the BTC price decreases by 50%. 

In case the trader assumes that the BTC price will be going up, they may increase the leverage to 10x by decreasing the margin amount accordingly - to 0.2 BTC. Thus, the trader will lower their risks. However, in such a case the position will be liquidated in case of a price drop of 10%.