This advice seemed to be very promising. Thanks.
The new problem is I can´t anymore even sign in on my profile for changing the login account. I tried that but I cancelled the operation, cause I wanted to use the same e-mail-address for a new login account also.
Naturally I couldn´t create a new account to previous email-address.
And after this I can´t log in from my itouch at all anymore.
So, I need to close first my account? Am I right? Not just overwrite it.
At this point you're not making too much sense, and I believe because you are confused. There is no need to close any account, or over-write. At least there shouldn't be.
Let's start over again:
Are you saying the Apple ID you see prompted is the same email address that is yours and you are trying to enter the password for it, but it won't accept the password?
Ok, we will try to get over this language barrier. I'm sure this problem is very simple to solve.
On your touch, I want you to first sign out. Tap this:
Settings > iTunes & App Stores > Apple ID > Sign Out
Now, sign back in with your Apple ID again, and enter your password. Once that works, you should be able to continue with the downloads.