Restore settings in games to new Family member accounts

I spent time today adding my son to the Windows 10 Family settings, and when we tried to access his account we learned that all his game settings, skins, standings, etc are all somehow connected to the main administrator account? He can't even access the Steam program or anything? I can't figure out how to set permissions by program. Help anyone?

I'm thinking that because I didn't set these settings and accounts up when we set up the computer he'll lose all the settings, but surely there's a way around this? Hasn't this happened before?

I'm thinking I need to set up a new Admin account and then turn over access to the original one to him?

Please...help?

I just checked and in fact, he has no access to most anything a computer could be used for - Excel, Word, etc. and only bare bones programs/apps. This doesn't seem to make sense to me.