If you use your Google Account name and photos for your YouTube channel, you can update this information at any time. If you change it anywhere, it will also change the name and photo across all your Google services.
To change your YouTube username, you have to follow these steps:
>Sign in to your channel on YouTube.
Go to ‘Settings’ by clicking on your avatar in the top right corner then clicking on the button next to the Creator Studio button.
In the ‘Overview’ section (direct link), click ‘Edit on Google’ next to your channel name.
Update the channel name and click OK.
If you want to use a name or photo on YouTube that’s different from what you have for your Google Account, connect your channel to a Brand Account. You can do this to support your business or brand identity on YouTube without having a connection to your personal Google Account.