Why does my child have to sign in as me to play games

My daughter has her own gamertag and xbox one. Before she can play any game she has to sign in as me, then sign me out, then sign in as herself and she can play. When she tries to play the game it says she doesn't own it. It's strange because
my son also has a gamertag and his own xbox one and he does not have any issues. I'm sure it's a setting somewhere but I just can't figure it out. Anyone else have this problem or have a solution? Thanks.

You should be able to set your Xbox as your Home Xbox. To do this, go to Settings > Personalization > My Home Xbox. It will ask you if you're sure you want to do this. Select the Confirm/Yes/Set as Home Xbox button. After doing
this, you should be able to let everyone on that Xbox enjoy most games you purchase (not every game might work).
MAKE SURE YOU SET YOUR HOME XBOX USING THE ACCOUNT WHICH YOU PURCHASED THE GAME FROM.

So how it works only 2 ways for other accounts to play games from your subscription or library via home game share feature which can only be done on 1 Xbox and you can play ur Gamertag on another, however, it won't allow an extra console unless your tag
is signed in first.

It will depend on which account you bought the games under. If you bought them under your account and her xbox is not set to the home xbox. She will not be able to play them without signing you in first.

Hola

tal vez tengas el control parental activado o tu hijo puso la edad correcta ya que si es menor de edad a lo que requiere el vídeo juego no lo dejara jugar.

espero aya sido de ayuda saludos.

If it's your only Xbox I would make it your home Xbox and that should stop the confusion.