What is the reason why the message sent by QQ becomes blue font?

Reason: The message mode has been changed to "Text Mode". You can set the font color when using the text mode. To solve this situation, just set it back to "bubble mode". The recovery method is as follows:

1. As shown in the figure below, when text mode is used and set to blue, the sent font will be blue.

Second, to return to bubble mode, click "Three Points" on the text input box.

Third, several options will pop up, and click "Font Selection".

4. Finally, click "Bubble Mode" in the font toolbar. After switching, messages sent by individuals will automatically return to the right side of the window, and bubbles will be displayed again.