LOCAL Password Problem

I am trying to resolve password issues - first let me make it clear that I can log into my Microsoft Account - that is not the problem ( I emphasize that because people keep giving me answers on how to change that and it is not an issue).  I have a brand new XPS with Windows 10 (big mistake should have gone with 7) in any case - I set everything up local password/MS Account password and an account for my child.  I have gone in and out of both then today my child tries to log into her page - can't no password works so I go in as Admin to try to see if I can figure out what the problem in - there is no option for me to change it (clearly says I am admin).  I then decide to go log in as local admin and see if there are options there - now it won't let me log into my local account anymore says that my password is wrong.  The passwords are the same - from day 1 I have used the exact same password for the MS and the local to avoid any issues.  The caps is not locked - I can log in to the MS but not the local anymore.  I had the local first - didn' t sign on to MS account until 2 days ago and it worked find until now.

My question is - I don't have much on this computer at this point if I reset the computer back to the beginning will be able to reset the local password?

And why can't I get the right to change my childs password - will deleting the account and resetting one help?

Thank you.