First login to your YouTube account, then click on that little grey arrow at the top right corner next to your user name. It opens a sub menu with a link to VIDEOS (by which they mean your uploaded videos).
Click on videos to see a list of your uploads. Pick the one you’d like to turn private by clicking the EDIT INFO button.
Further down under Broadcast and Sharing Options you’ll find three options that define who can see your creation:
means that everyone in the whole wide world and view and share your video. It will come up in YouTube and Google searches. So this option is – you guessed it – 100% public.
means that only people who you give the direct link to will be able to see the video. It’s still “public” as in every person with said link will be able to view the video, but you won’t come up in YouTube and Google searches. Choose this option for the 30 Day Challenge. Your links will only be shared on a secured page so nobody will see these links other than 30DC members.
means that only you can see the video, unless you specify other YouTube members who in turn will have to be logged in to YouTube to view the video. It’s the most private option there in on YouTube. Your videos are 100% locked down and won’t appear in YouTube or Google searches. Even if you share a link to your video, the other party won’t be able to see it unless you’ve specified them in the list below and they are logged in to YouTube. Please note that you can only share a private video with up to 25 other YouTube users, so don’t use this option for the 30 Day Challenge.
You can always change these settings on a per-video basis if and when you please – so you if ever decide you want to go public (or private), all it takes is a mouse click. YouTube videos will be available “forever” – they said that no videos will ever be deleted from their system.