How to enable the Douyin sing-along mode is as follows:

1. Open the Douyin app and enter the main page of Douyin.

2. Click on the shooting page at the bottom of the screen and click on the option to select music.

2. Select the music name and check the soundtrack option.

3. Click the sing-along button at the top.

4. Successfully enter the sing-along mode, click the shooting button at the bottom to start singing along.