Is it only minifigs that appear blurry?
Do you use any depth of field settings in Mecabricks or Blender? These might be not ideal.
Maybe you could upload a sample image to imgur.com and post the link here.
Thank you for your help! Yes, it's my minifigs that appear blurry/fuzzy. I don't use any settings except choosing the color of the floor and walls when I'm rendering because I'm a newbie to Mecabricks. I'll try sharpening them, thank you!