Edit german content for my web page

I have a German text that needs to be edit-
ed. It is a questionnaire for the tax declara-
tion app. Many sentences repeat several
times in the text and differ only by 1 word.
Language used should be as simple as pos-
sible. Text should be per" du ". Currently
some parts are written in active and others
in passive - text should have a consistent
style.