Everyone seems to have issues with the WordPress editor at one time or another. It seems to have a mind of its own and will do things to your content that you don’t want done.
One issue that seems to occur occasionally is when your text content creeps up around an image even when you tell it not to. No matter what you do, you can’t get the image to simply sit above the text and be separate from it.
Here’s a solution that should solve your problem.