The steps to lengthen the photo music in this software are as follows:

Tools: mobile phone, "Cut Screen".

1. Open the clip and click to start creating.

2. Select the photo material and click Add.

3. Click on the audio option.

4. Click on the music option.

5. Select music and click the Use button.

6. Press and hold the button on the right side of the music timeline and drag it to the right to lengthen the music time. After adjusting to a suitable time length, click Export.

7. After exporting, click the option to share to Douyin.