Can't set or change my password nor login from a different computer

Hi everybody!
I just sent you my email-address (no facebook etc), received an email with a one time pin (OTP) code and with this code “logged in” and started to code. Now I almost finished Responsive Web Design Certification and tried to log in from a second computer. It is not possible because I have no password. Back to my first computer, where I am still “logged in” I don’t find any possibility to set or change a password.
What if I want to continue on a different computer but can’t log in?
Do I have to request a one time pin (OTP) code each time I want to log in?
Will I loose my progress when I log out on my first computer?
I find the account policy somehow puzzling.
What should I do?
Thanks in advance.

if you log in with email, you will need to request a OTP and log in with that each time you want to log in, yes, you need to request it each time

use always the same email address and you will be able to log in from any computer