Hello Mrasdfghj,
I understand how frustrating that can be. I have multiple devices and use Screen Time on some of my old phones so that my friends can play around with them and not mess up my accounts or get into personal stuff. I have seen this issue myself and it is one of the most annoying things I’ve dealt with. The only fix I’ve been able to figure out on my own that will keep it from resetting itself is to turn off Share Across Devices.
The reason why it kept resetting with this feature turned on, as far as I could see, was because I kept different settings on my main devices compared to my old phones that I kept under extreme restrictions. You can enable or disable this setting in Screen Time Settings, which is under the set/change/turn off screen time passcode. You’ll need to do it on your kids’ devices and sadly, when you do, it does reset the entire screen time settings. But once the setting is changed, your issue should be resolved. If this doesn’t work, let me know and I’ll send you some more info. Good luck!
Sincerely,
Captain