To set the interchangeable specialty sound effects in Douyin, you can follow the following steps:

1. Open the Douyin application and log in to your account.

2. Click the "plus" button in the lower right corner to enter the video recording page.

3. Find the "Music" option above the bottom toolbar and click to enter.

4. Search for the specialty sound effects you want to use in the music library. You can try to search for keywords related to specialties, exchange, exchange, etc. to find suitable sound effects.

5. Click to select the specialty sound effect you like and preview whether it meets your needs.

6. In the sound effect preview interface, you can adjust the start time and end time of the sound effect to control the playback duration of the sound effect.

7. After confirming that you are satisfied, click the "√" icon at the bottom to apply the sound effects to your video.

8. After completing the above steps, you can continue to record your video, and the sound effects will automatically play and synchronize with your video.