I use it to create a new admin account. I NEVER use it to touch existing accounts.
Here's a tutorial. https://www.google.com/search?q=utilman.exe+create+admin+account+windows+10
Also, I can reset most PCs by using a Windows 10 Repair and Install DVD or USB stick. These are free to create with the (link only) https://www.tenforums.com/tutorials/2376-create-bootable-usb-flash-drive-install-windows-10-a.html
I change the password by making utilman cmd and net user. It says successful but keeps going right back to DefaultAccount. The network connection on login shows red x. No option to reset PC. Major problem anyone seen this or have ideas?