It's usually quite difficult to prevent people from changing things in Word documents. One approach that people sometimes use for positioning pictures is to insert the image in a header/footer and then position it. That doesn't prevent users from moving it, but it makes it less likely that they will delete it accidentally. But then the image behaves like a watermark - you cannot specify wrapped text etc.
The only way I can think of that would also allow normal editing (well, almost normal) in the rest of the document would be as follows. I have never used it, so you would need to find out whether it prevents the user from doing things that they need to do (e.g. edit headers/footers and so on):
- insert the picture and format it how you want. Make
sure it is anchored to the first paragraph in the document, and lock the anchor (In the Picture Position->More layout options->Picture Position tab).
- Insert one more paragraph
- Format the first paragraph to be exactly 1pt high with no space above or below (i.e. reduce its height as much as you can)
- Select the second paragraph
- Using the Developer tab (which you may have to enable in order to do this), click Protect Document->Restrict formatting and editing.
- Check "Allow only this type of editing in the document"
- Select "No changes - Read Only"
- In the "Exceptions" box, check "Everyone".
- Click "Start Enforcing Protection", and assign passwords if you really don't want the user to change the picture position.
You will see that editing looks a little different from usual.