What happen to the other ScreenTime code on my daughters iPhone?

Seems it is up to the parent whether the child or the parent can control the sceenTime settings.

If you wish, you can:

"Lock Screen Time settings

If you didn't set a Screen Time passcode during setup, or turned it off and want to lock your settings again, you can set a passcode in Settings. That way, only you can change Screen Time settings and any parental controls that you set.

1. Open the Settings app.
2. To lock your Screen Time settings:

• • Set a passcode for your device: Tap Screen Time, then scroll down and tap Lock Screen Time Settings.
  • Reset a passcode for a child's device if it was turned off: Tap Family, choose the child, then tap Lock Screen Time Settings.

1. When prompted, enter a passcode, then re-enter it to confirm.
2. Enter your Apple ID and password.

Above comes from Apple Support's online article:

Use Screen Time on your iPhone or iPad - Apple Support

Hi Rgreen93,

welcome to the Apple (user-to-user) Community!

Re: "What happen to the other ScreenTime code on my daughters iPhone?"

Seems it may depend on how you have ScreenTime set up to operate.

if your daughter is in a Family Sharing group for which you’re the organizer,

you can set up Screen Time for them through Family Sharing on your device.

Else:

You can set up Screen Time for a family member on their device following the steps

in Set up Screen Time on iPhone

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Re: "There use to be a code you enter before even further in screen time but now I don’t know what happen to it.

It is like they can go on their phones and change screen time whenever they want".

You may want to view what to do: If you forgot your Screen Time passcode - Apple Support

Eg: In the linked article above:

Check under the heading: "How to reset the Screen Time passcode for your personal device"

or

See "How to reset the Screen Time passcode for your child's device"

If you’re using Family Sharing to manage a child’s account, the family organizer needs to reset the passcode on their device.

All the best :-)