In order to add a new YouTube channel to your account following initial account creation you will follow these steps:
Access Settings located in the profile drop down in the upper right of your dashboard
Select the channel name located in the lower left of the settings pop up
At the bottom of the pop up you will see a list of all linked YouTube channels
To add: Select the "Add" card
To remove: Select the three dots attached to the channel you wish to remove, and select "remove"