The first thing we need to understand is that we are trading in the form of a match transaction. When the buyer and seller have the same price then the transaction will be completed.
As shown , on the right side of the trading page , there are "sell orders" (red) and "buy orders" (green). It can be seen that the current selling price is 0.1292, the buying price is 0.1285, and the market price is 0.1288 .
If the user wants to complete the transaction quickly, they can only match the current best price. If the user sells, it needs to be matched with the buying price "0.1285". If the user is buying, it needs to be matched with the selling price "0.1292". If the price is just match the market price, then it won't be sold until the best price is reached.