1. First, open the Tik Tok application and log in to the account.

2. Secondly, in the bottom navigation bar, click the "I" icon in the lower right corner to enter the profile page.

3. Then, at the top of the profile page, you will see your avatar. Click on the avatar area.

4. Finally, this will open an editing page, where you can choose to choose an existing photo from the album as the avatar or take a new photo.