A great advantage of 1KA is that you can always add questions to the questionnaire later on, even when the survey is already active. While the survey will automatically lock after activation, you can unlock the editing of the survey by clicking on the padlock icon that appears on the left menu for adding questions in the 'EDIT' - 'Questionnaire' tab or next to the survey URL at the top of the screen.
In this case, missing values will appear for respondents who have already answered the survey and have thus not received the newly added question. The previous respondents' answers to the new question will be marked with a value of -4, indicating a later added question, which - like the other missing values (-1 non-response, -2 skip, -3 abandoned survey, -5 blank survey) - will not be taken into account in the analyses. For the already existing questions, no changes will be made by adding a new question.
You can also change the order of questions and categories during the survey without any consequences. You can add new response categories (e.g. for "Eye colour?" you can add "green" afterwards in addition to "blue" and "brown"). Of course, you should be aware that the new category will have a lower frequency of occurrence overall than the initial categories that previous respondents have already been able to choose.
Care should also be taken not to remove any variables, as this will also remove the corresponding data in the database. If you find in the middle of the survey that you no longer want a particular variable (or condition or block), simply hide it in the editing process and it will no longer appear to respondents.
However, it is worth noting that in principle, revising an active questionnaire is a delicate operation that many survey tools either cannot or do not allow. In fact, if the frequency of responses is high, some respondents may receive a question that is somewhat incomplete due to it being added right before they began to answer the survey. Some editors therefore prefer to lock the survey for editing after activation.
The approach you take will therefore depend on the nature of the circumstances, but for a small intervention (e.g. one question or one category) and a smaller survey, where new responses are not coming in every minute, a live intervention is by far the most effective and sensible approach. In any case, it is advisable to make an archive copy before making any changes to the questionnaire. If you change anything, the old version will not be saved without creating an archive. Archiving of the questionnaire is only available for users of the 2KA and 3KA packages for individuals, and for users of the business packages for groups.
If you delete a question, the data for all existing answers to that question will also be deleted.