Depends on how you're using the software. Some don't even set the username field, so it doesn't matter. And those that do, you have to create a new account in the software to set the username to the password (MUST make folders to put them in)
As the username is part of what generates the password, you might want to set that up before setting/changing the password.
If I'm off the mark, you might need to explain what you need a little better.