Select an image and click the toolbar icon to bring up the image toolbar. The toolbar contains these commands: (not all commands are available on all platforms)
image toolbar - send to back Send to back - rearranges the image behind other images in the same containing topic.
image toolbar - bring to front Bring to front - rearranges the image before other images in the same containing topic.
Copy Copy - copies the selected image to the clipboard. Use "paste" from the topic toolbar to paste the image into another topic.
Edit Image Link - change the image link that is opened when double-tapping the thumbnail.
Add image or video Change Image - select a different image or photo.
Rotate - rotate the image. Use the two-finger rotate gesture (iPad/iPhone only).
  Note, next to the topic toolbar is the "lock image" icon. This will lock the image in a fixed place.