To prevent images from moving unexpectedly when you change page orientation, you should anchor them to a specific part of the text that will remain stable through the change, or place images within text boxes. When using text boxes, you have more precise control over the placement and can lock the text box's position. Additionally, ensure that the image's wrapping style is set appropriately (for example, to 'Tight' or 'Behind Text') to maintain its position relative to the nearby text.