1. First, open the idle fish program in your mobile phone, enter the home page and click the "My" option in the lower right corner.

2. Then click on the avatar position at the top of the page, and you can see an arrow icon on the right side of the avatar.

3. Open the personal homepage and click the "Edit Data" option in the upper right corner.

4. Enter the profile editing interface and click the "Nickname" option.

5. You can enter the nickname modification interface, enter a new nickname in it, and then press the Save button.