Hello there and welcome to Just Answer. My name is ***** ***** I will be assisting you today. I am an engineer with over 30 years of electrical and electronic training, repair and installation experience. I will try and answer your question accurately and precisely so that we can get you on your way.
Do you have 'Auto ISO' switched on and maybe set too high? Pick one of your 'noisy' images and look at the image details (press 'down' on the multi selector). What is the actual ISO on that noisy image?
Let me know.