Unfortunately that particular customization is not available in Cloud environments. However, if you would like to see it available in future releases, you can create the idea for it here Ideas for Jive so that other can vote it up.
i back your idea regarding the requirement to be able to customise the Type your question text within the Ask <Community Name> Widget.
I am currently trying to use said widget as a 'Create a Post' widget on our home page to encourage users to post discussions in our community.
Whilst we can re-title the widget and said button, there's no point if we cannot customise the widget's look n feel in its entirety.