Hi @thùy anh
At the taskbar, click on the speaker icon, then click on the speaker name, there should be a list of speakers to select, select the one you desire.
Or go to Settings > System > Sound, Under "Choose your output device", there is a box that you can change your output device, or if it doesn't work, try running the troubleshooter in the same settings menu.
Hope this helps!
Best regards,
Nanta