Hi, there's nothing exactly like this built-in to the software. There is no easy way to test whether or not a User has changed his/her password from the automatically generated password. I suppose you could try to work around this with a custom field somehow, like if you set a value of 1 in a custom field when the User registers, then set the value to 0 when they submit an Edit User Form. In the site, you could test the value of that custom field and display an Edit User Form instead of the site content. But even that isn't foolproof, as there is no easy way to test whether or not the User changes his or her password in the Edit User Form - they could change other information without changing their password, and that would update the custom field value.
So the short answer is there isn't a good solution for that problem, but you could try some alternatives to force the User to submit an Edit User Form.