You can change your public username by logging in to your account and going to your profile page.
Click on the dropdown menu at the top right of the page next to your profile icon and click on 'My profile'. Then click on 'Edit profile'.
Scroll down the page and you can then enter a new public profile name. Please remember to save the changes!
If you are a project creator whatever you enter in the box will show up on your project page or pages.
If you are a pledger your profile name will show in the supporter history.