The Question Explorer (found on the left side of survey admin area), lets you view your survey structure -- question groups, and within each group, the associated questions:
To edit a question, use the Question Explorer to find your question, and click on the question text to go to the Question Summary page.
From the Summary Page, you can edit the text of the question, change the question type, and in the case of non-open text type questions, edit the sub-questions (like multiple choice answers, radio list items, and arrays (row and column text). See the image below for a quick overview of the features found on the Question Summary Page:
Editing Multiple Choice, Radio, and pre-defined Array types:
You can edit the options they are shown (sometimes referred to as answers -- although we use the term answers to mean what a respondents responses to -- not what we show them) by clicking the Edit subquestions button. When you do this, you'll see the options displayed to the participant.
Editing Custom Array type questions:
The "Array" type question allows you to specify both the row and column values. On the Question Summary page, you'll see buttons for both sub-questions and answer options. Sub-questions are the rows, and answer options are the column headings. In the screen shot above, you'll see Edit subquestions and Edit answer options, when editing an Array type question.