Yes, you can change your username up to three times only.

To change your Username:

For Android:

1. Tap on Profile icon item on right down corner.

2. Tap on the 3 dots menu and Tap Settings menu item.

3. Tap on Account Information. and tap on what information you want to edit or change.

4. Tap on the pencil icon next to your Username.

5. Edit your Username.

6. Tap on Done on the top right corner of the screen.

For iOS:

1. Tap on Profile icon item on right down corner.

2. Tap on the 3 dots menu and Tap Settings menu item.

3. Tap on Account Information. and tap on what information you want to edit or change.

4. Tap on the pencil icon next to your Username.

5. Edit your Username.

6. Tap on Done on the top right corner of the screen.