Go to your Velop client page URL (ie. https://rdn.velop.org)
Click on the Log In tab in the top right

Click on Forgot Password


Enter your account email and verify that you are human
Click Reset Password


Check your email and follow the link sent to you
Follow that prompt and a new password will be sent to your email. 

If you want to change your password once you're logged in, mouse over your name in the top left and click on Password. Change your password there by entering your old/temporary password