Choose to create a new channel or use an existing Brand Account:
Create a new channel by clicking Create a new channel.
Create a YouTube channel for a Brand Account that you already manage by choosing the Brand Account from the list. If this Brand Account already has a channel, you can't create a new one—you'll just be switched over to that channel if you select the Brand Account from the list.
Fill out the details to name your new channel and verify your account. Then, click Done. This creates a new Brand Account.