Make sure to set sign off: off (don't forget the keyword).
sign off: off
Be sure to use the run link (not preview link) when you use the survey for real. If you do that, then sign in is not required. The run link can be found on the share page (which you can access from the edit window for that program). There is a setting on the settings page that requires sign in but that is off by default. If you turned sign in required on you’ll have to turn that off.