Layers and Images - Send to Back and Bring to Front

I have several layers created for a single slide, i.e. Happy, Sad, Angry, Excited, etc. Each layer has a caption box on it with appropriately created text in it. I have a character on the main layer which changes expressions based on the layer which is displayed after a learner clicks one of several buttons on the main layer. Issue: the captions which are on each layer display on top of everything else, i.e. the character's hair, arm, leg, etc. I would like to make it so that the text caption boxes are always "Sent to Back" regardless of which button is clicked on the main layer. How can this be done? I have tried the "Send to Back" command for each text caption and this does not work. Do I need to do this via JS? If so, has anyone done this before and would you be willing to share the script so that I may achieve whay I am setting out to?

Thank you in advance for your assistance!