Switching Channels
To switch to a different channel that you manage, there isn't any need to log out. With YouTube selected in the Destination menu, go to the Ecamm Live menu at the top of your display beside the menu, and select Change YouTube Account. You will then be able to pick a another YouTube channel that you manage.
Switching To a Different Login Account
If you need to switch to a channel managed by another account, you'll need to log out of YouTube.
With YouTube selected in the Destination menu, go to the Ecamm Live menu at the top of your display beside the menu, and select Log Out YouTube. You can then click the blue Log In button to log in again.