Follow these steps to update your profile name:
Click on your profile image at the top right corner of the app.
Then select “Account settings” from the profile menu.
Under the “Profile” heading of the Account settings modal, select the “Update” button to the right of your current profile name.
Then enter your new first and last name and your password.
Lastly, to confirm the change, click the “Update name” button.
And that's it.