There's even a component that converts your syntax if changed.
Thank u so much!
1. After the installation process, delete configuration.php (+ the intallation-folder, of course) before trying to access the site.
2.Use the same login-details as before! At the end of the installation-process, it gives you the loginname and password for administration you typed on the page before (as in a standard installation). If you decide to use an all new password, it's not gonna work; the old one from ther earlier installation is still active. That's actually great! Except that you shouldn't trust the screen if you just typed a new one ;)