How to swap to USDT on OKX app?

Hello there, I'm curious about the process of swapping my cryptocurrency holdings to USDT on the OKX app. Could you please guide me through the steps in a simple and straightforward manner? I'm particularly interested in knowing if there are any fees involved in the process, and if there are any precautions I should take to ensure the security of my funds. Additionally, I'd like to understand the benefits of holding USDT on OKX, compared to other stablecoins or fiat currencies. Thanks in advance for your assistance!