To upload background music to Kuaishou on your Apple phone, just select the original music when making a video in the Kuaishou app. The specific method is as follows:

1. First open Kuaishou and click on the upper right corner to record Video button.

2. Go to the video recording page and click the music button in the lower right corner.

3. Select background music for the video and click the third option above the menu, Local.

4. In this way, you can choose the music on your iPhone.

5. After determining the music, you can directly start shooting or edit the required parts.