LOL Your not wrong but missing something important.
Yes the user can change the user database setting in the Photopost admin section under options. CORRECT
However if you have it set wrong and can not login how are you expect to be able to login and change it to the right one.
Thus using PhpMyAdmin and correcting the setting is the normal way to do it. I can not tell you how many times people installing Photopost forget to set the correct user system.
There is a third way to do this as well. You can always upload the install.php file and rerun install on a new install and make sure you select the proper user registration on that last install step from the drop down box.
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