How do I ensure website update render images correctly

I have images at the beginning of key paragraphs on my site that in editing mode are exactly as I want them to appear when published but they render as huge blurred images that are centred above the paragraphs when I preview and /or update, and nothing I have tried seems to make any difference. I have edited the images for size/dimensions etc but all to no effect. One of the pages had been rendering just fine until I moved it to another page on the site - same again- large blurred image above para, even when I moved it back it would no longer render the edit.
TRied looking to see if it was a page setup issue but then it should have reverted when I moved it back...???
Thanks
TJA