Need Help with Annke DVR System

Hi hope some of you guys can help. Need a little help with a system that i bought recently, the system in question is an Annke 8CH 1080P CCTV DVR www.amazon.co.uk/Security-Camera-8%C2%A1%C3%812-1Megapixel-Outdoor-Pre-installed/dp/B01A81AKUA?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o09_s00

So recently bought and installed the above item with little dificulty but the thing that has me is the picture quality, the images during the day and at night time seem to be grainy alot of what it seems are white dots. I have changed the image quality to 1080p and input to hdmi but nothing really has changed. If any of you guys could help i would very much appriciate it.

thx for reading

Just a quick update, on 3 of the cameras there seems to be shadows moving from left to right across the screen continuously, tried turning the machine off and leaving it for while but when the system was turned back on the shadows are still there

Thanks for the help guys " title="Applause" />