Your Boost (for 3 or 5 channels) or Enterprise subscription allows you to add and manage multiple YouTube channels at the same time.
To do so:
Navigate to the top-right corner and click on your icon.
Click the "Add Channel" button
Click on the “Authenticate your YouTube channel” button.
Sign in to the Google account associated with your YouTube channel.
Choose the channel you'd like to add to vidIQ.
Allow access to your channel by clicking the “Allow” button.