Can I still make changes to my survey if I have set the project status to active?

Yes, you can still make changes to your survey if it has the status active. However, you should not make any more changes if the survey has already been sent to the participants and the questionnaire is live. Changes to the survey can cause data to be lost, for example, because you have deleted a variable. For this reason you should perform a long pretest phase before the Go Live and test the questionnaire extensively.