Greetings Andrea9h5,
We understand that even after creating a new Screen Time passcode, your children are able to bypass your parental controls. This is definitely unexpected behavior. Therefore, we'd like to provide you with some information that may help to resolve this issue:
"Make sure to choose a passcode that's different from the passcode that you use to unlock your device. To change or turn off the passcode on your child's device, tap Settings > Screen Time > [your child's name]. Then tap Change Screen Time Passcode or Turn Off Screen Time Passcode, and authenticate the change with Face ID, Touch ID, or your device passcode."
We also suggest that you verify where changes to the settings can be allowed. Here's how:
"1. Go to Settings and tap Screen Time.
2. Tap Content & Privacy Restrictions. If asked, enter your passcode.
3. Under Allow Changes, select the features or settings that you want to allow changes to and choose Allow or Don't Allow.
Here are some features and settings that you can allow changes for:
• Passcode Changes: Prevent changes to your passcode
• Account Changes: Prevent account changes in Accounts & Passwords
• Cellular Data Changes: Prevent changes to cellular data settings
• Reduce Loud Sounds: Prevent changes to volume settings for safe listening
• Driving Focus: Prevent changes to the Driving Focus
• TV Provider: Prevent changes to TV provider settings
• Background App Activities: Prevent changes to whether or not apps run in the background"
For more details, check out: Use parental controls on your child's iPhone, iPad, and iPod touch
If you continue to experience the same behavior, please reach out to Apple for further assistance. You can follow this link to connect with them: Get Support
All the best!