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.
Your profile page has an "apps" tab:
This is not the same thing.
That tab shows apps that you have authorized to access your account. EG:
Note that the first 2 entries are not apps that I developed, and most of my registered apps are not listed in this tab. Only the ones that I have also logged in with via OAuth are shown.