There are 2 key places where you must select public for a video to be available to share publicly. If they are not set to public, you can't share, end of story.
These images are from the YT app on my phone, but it is similar on the desktop version through a web browser.
So, your playlist must be public.
And you must make the video available to the public within that public play list. I think you can get away without using play lists but that's rather like storing everything on the floor.
So check your playlist area first.
Then, click add.
Visibility must be set to public.
I find it less hassle to say no to kids.
Select a playlist that is visible to the world
When it has uploaded, click the 3 dots and select share
Copy the link.
That link is what you paste here.