A tip I would suggest is to not recreate assignments and quizzes on formative. You can upload a current electronic document from Google docs, Word, PDF, etc. into a formative. Makes creating a formative so much easier and gives you great data at the end.
To make it more difficult for students to google questions, type out your question in Word or Docs, then screensnip the questions individually. You can then just paste it into the formative question box and your students can’t copy/paste the text into google as easily. You can also then scramble the question order (which you can’t do when you just straight upload a word doc or pdf.