Once you have create a survey you can edit the name by clicking on the title and entering a new one.
You are also able to make changes to any of the individual questions within the survey by selecting the question and pressing it's respective edit button.
Question can also be re-ordered in a survey by clicking the top bar for each one and dragging it into it's new position.
Once a survey has been started it is no longer possible to make edits.
If a survey is started and then subsequently stopped the only situation where you are still able to make any edits is when there are no responses gathered for that survey.
If you want to make edits to a survey that you have already started gathering results for then you will need to Duplicate the survey first. You are then able to make edits to the fresh version of the survey without effecting the validity of any responses you have already gathered.
Alternatively if you have just been doing some testing you can clear the results of the survey. Once results have been cleared you are also then able to edit the content of the survey again.