Futures is a daily debt-free settlement rule. After the close of the day, the settlement price (average price) is used instead of the closing price. When the settlement price is inconsistent with the closing price, the book profit and loss will naturally be different. This is just a settlement rule, which has little effect on your income. If the market is strong or too weak the next day, there will be a gap. At this time, if you go in the right direction, your book profit will increase greatly, much more than the income from closing the position that day.