I registered two apps in Stack Apps, but when I access my account, it shows no registered apps.
How can I mark them as my apps and how can access app settings (client id, key), etc?
You can see your apps, that you registered with the registration page, by going to:
This page is different for every user and you will be forced to log-in to see it.
The only place I have ever found this link is in a sidebar on Stack App's home page: