If you are already registered in the store, you can change your password on your own - either because you forgot it or because it makes sense to change a password from time to time.
What do I have to do
In the login screen of the store you will find a line with:
I have forgotten my password (Ich habe mein Passwort vergessen)
If you click on this link, you will automatically receive an e-mail to your registered e-mail address with the information that you now have 2 hours to change your password.
So please check your mailbox or spam folder immediately and change your password.