As follows:

Tool: Huawei P20

Operating system: EMUI 10.0

Operating software: Alarm Clock 2.0

1. First, find the alarm clock on your phone and turn it on.

2. Select the alarm clock to set a new ringtone and click.

3. Click the ringtone.

4. Click the + in the lower right corner of the page.

5. Select local music in the menu interface that appears and click to open.

6. Find the song you want to set as ringtone and click the circle next to it.

7. Click the menu at the bottom to confirm. This will successfully add the new ringtone.

8. Click on the song you want to use in My Ringtone, and click Apply on the right.