Your welcome 3 ways?
I have seen this written:
どういたしまして
Then, the same way but with the "いた" written in kanji
The the same word with どういた part written in kanji and the rest in hiragana.
(I apologize, but my MME will not let me reproduce the kanji for these characters like I seem them in my kanji dictionary app or the way rikaikun displays them which is how I observed that there are three way of writing this form of your welcome).
I actually notice this quite a bit when reading text. If I hover over a word that happens to be written in kana, rikaikun will show me the word, and it's meaning, with part of it written in kanji even though the Japanese author chose to write it in kana.
Can anyone explain this to me? Thank you.