Images can be hard to select in Word when their text wrapping is set to Behind Text. I often place images behind the text in, for example, a document cover page.
To select images behind text:
- On the Home tab, go to the Editing group, and click the Select down arrow.
- Choose Select Objects.

Click on hidden objects with the Select Objects pointer and move them manually or click on the down arrow on the Bring Forward button in the Arrange group to Bring Forward, Bring to Front, or Bring to Front of Text.