I'll look it up and see if there is a way to add another Local Account when the other doesn't log in due to forgotten password. If another Local Account can be made then just have to get in with the Secondary Local Account change it to be Administrator then you can change the password to the one forgotten. Once it's changed you change the account you are going to use back to Administrator and then delete the secondary account.
Give me a few minutes I'll have a look.
EDIT: The only way to make a Secondary User Account is through a Command Prompt setting. Your Son should be able to help you with that and get it going for you.
Just Google, Forgot My Windows 10 Local Account Password and there are lots of Tutorials and YouTube Videos to show how the process is done.
It's a little different than the other Operating Systems. After a Secondary Local Account is made, the rest is as easy as a Walk in the Park.