Problem with changing a headline in a cloned document


I created a questionnaire and all worked good but now I tried to create a new one and cloned the first one, because every question is the same only the headlines changed. I tried to change the headlines, but it doesn´t work. Furthermore I can not make a group and give the group-line a name, I can´t write there anything.
What I have to do? Can you help me please?

Best regards,