Why has Keynote slides format changed A4 over night

Over night all my slides content shrunk and when printed appeared as if reduced to 94%. I wondered why. I never change any settings for past year. Was there an update on 7th or 8th September. I have tried 4:3 and 16:9 setting but why should I. what was on the screen on standard A4 is what I want printed as a slide?

Help as now my file is useless too!