In NetWorx, the name shown in reports comes from your Windows login name (the account you actually sign in with), not the full name that may be additionally stored in Windows.
To check this, open a Command Prompt, type
whoami
and press Enter. The result should be the same name as NetWorx shows.
Windows does keep a separate "full name" field for accounts, but that isn't what NetWorx uses. That's why you are seeing "Michael" instead of "Michael Lastname".