When you go here: http://www.redapp.org/user/password

and enter your email or username, and click the button at the bottom of the form  the system emails you a onetime link. 

you open the mail click the link and you arrive at redapp and see a login button - Click the log in button -  just works without a password.

you are now in your account where you only have to enter a "new" password.

enter the new password twice and scroll to the bottom of the page and click save.

 

you are now logged in and your password is changed.

 

You should logout and login with your username (not email) and password to test it.