It is really simple to add a YouTube channel to your Grabyo account, you can follow these steps and when prompted select to add a YouTube account. From here you will have to sign into a Google+ account which is linked to your YouTube channel, and then allow Grabyo access to post to the channel.
If you have a YouTube channel selected as a destination when you press the 'save & share' button a YouTube popup will appear on your screen. Here you can configure the title, description and the privacy status of your clip. Once you have filled out this information you can press the 'share to YouTube' button and the video will begin sharing to YouTube.
Once you've shared the video you can then go into your YouTube channel and make any playlist changes or enhancements through the YouTube video manager.
Please note that the YouTube channel that you are sharing to needs to be "verified" on YouTube to be able to use a custom thumbnail. If your channel is not verified your clip will still share to YouTube but the thumbnail you selected in Studio will not be reflected in YouTube.
You can check that your YouTube channel is enabled for custom thumbnails by going to www.youtube.com/features. In your account you will be able to see the below page, when verified your 'Custom thumbnails' feature will have a green status.