How to press enter to send a message and automatically close the chat window?

Hello! This is because the message mode is set. Open a new chat window, and then click the small triangle to the right of "Send". At this point, you will find a "message mode" in the drop-down box that appears, and there must be a check mark in front of it. If you click Message Mode, the previous check mark will disappear. After chatting with friends again, the chat window will not close automatically.