Just tried to find the content filter and apparently its only available on android, and in other countries..UK wasnt listed
That will be why when they got them I couldn't find a content filter, but seeing all this about 'parents can chose which channels the kids can see' and such..made me think it was now an option, seems not. Also I thought YT kids already had a content filter due to being..well youtube kids, where surely adults check the uploads, rather than relying on reports like they seem to do on normal youtube.