https://support.google.com/youtube/answer/9527654
This is a result of Youtube and Google complying with a court order and the FTC.
Note:
To set your audience as made for kids, you'll need to do so in YouTube Studio. You won't be able to do so in Creator Studio Classic.
We'll make the audience selection tool available to third-party applications and the YouTube API Services in the near future. For now, please use YouTube Studio to upload made for kids content.
Important: Why every creator must set their audience
These changes are required as part of a settlement with the US Federal Trade Commission (FTC) and NY Attorney General, and will help you comply with the Children’s Online Privacy Protection Act (COPPA) and/or other applicable laws. Regardless of your location, we require you to tell us whether or not your videos are made for kids. If you fail to set your audience accurately, you may face compliance issues with the FTC or other authorities, and we may take action on your YouTube account. Learn more about the FTC’s enforcement of COPPA.
Note: We’ll also use machine learning to help us identify videos that are clearly directed to young audiences. We trust you to set your audience accurately, but we may override your audience setting choice in cases of error or abuse. However, do not rely on our systems to set your audience for you because our systems may not identify content that the FTC or other authorities consider to be made for kids. If you need help determining whether or not your content is made for kids, check out this Help Center article or consult legal counsel.
This is a result of Youtube and Google complying with a court order and the FTC.