To add or edit a factor to a survey you need to go to Manage Surveys
And then press edit on the survey you want to edit or add a factor to.
When in the edit view press add new factor to add a new factor
Give it a name.
Then type out your question in the Question field.
Choose your answer group.
in 99% of the cases you do not need to change "Numeric", "Multiple-choice question" or "Unit" so just leave these as default.
Order in survey: This decides where in the survey this question will be. So 1 is the first question, 2 is the second question and so on.
Unless you are doing advanced survey set-ups then "Should the question be shown based on an answer to another question" should be left to No.
Mandatory: Decides if the customer is required to answer this question.
If you just want to edit a factor just press the edit button beside the factor and you can change the same things as when creating a new factor.