We don't say any of your expressions. Give some context so we know what you are trying to say. In summary, .... To summarize, ....

For in front of 'change' and 'complete' is incorrect. You can sometimes use it in front of the '-ing' form, but it's not that common, and I can't think of a good example that would start with 'for answering'. Although you could say 'For answering the question on the form, use only black or blue pen' - that would be better written as 'When answering the question on the form, use only black or blue pen'. Other verbs, where the 'for' means 'for the purpose of', it could be OK - 'For cutting ceramics, you need a diamond saw'.