I have created a a user form in Toolset - see screenshot, front end is not showing how to create an account with the fields nickname, username and password missing from the form.
If you see at top right part there is a section "Options" and if you see that there are checkbox checked for "Auto-generate Username", "Auto-generate Password", "Auto-generate Nickname".
If you do not want to auto-generate those entities, you should just uncheck those checkbox and save your form and check on frontend.