Change picture - several instances at once?

Hi there,

I have an image in my eLearning that I use a lot throughout the course. I need to change this picture to a new one, but when I select several pictures at once the "Change Picture" function does not work.

Is there a way to change this image in all instances or do I have to change each one separately (which will take forever!)?!

Thanks in advance,

Mandy