^this. He is naruto namikaze but they did not want him to know (Hence minato was the 4th hokage) so they named him naruto uzumaki and it stood that way.Possibly to hide the fact he is the son of the yondaime for the public
This^it was said somewhere to hide the fact he was his 4th's son, as he apparently had alot of enemies who might carry out revenge on his son