There is no zoom in, zoom out tool in Premiere Elements. Do you mean the Pan and Zoom Tool?
If you are referring to the Pan and Zoom Tool and just its Zoom option
a. You select your Timeline still, go to Tools Menu and select Pan and Zoom.
b. In the Pan and Zoom workspace, you decrease the size of the frame (also referred to as focus frame) for the zoom in and increase the size of the frame in the next frame to zoom out (if you want a zoom in and zoom out effect)
The aspect ratio of your Pan and Zoom workspace screen will depend on the project preset's display aspect ratio.
If you select your Timeline clip and go to Applied Effects Tab/Applied Effects Palette/Motion Panel expanded, you can use the Scale property there to zoom in or out for your still. Do you just want to zoom in on one still and not zoom in and out within the same still? If you want to do the zoom in and out within the same still, then you need to keyframe the Scale property for Zoom.
You can just click on the Edit area monitor to bring up the images bounding box and then drag on one of the bounding box handles to zoom in or out in one still.
Please let me know if the first mention works for you or whether or not you need more information on it or other ideas.
Please ask if you have any questions or need clarification.
Thank you for the help ATR, Jim Bates
In one of your threads, you said that you did not see my reply.
You seem to be saying in this thread that you found my reply numbered 1 here.
Are you OK with the details or need for me to go into greater detail on the Pan and Zoom Tool for just Zooms?
Just checking to see if you had time to try the Zoom portion of the Pan and Zoom Tool to get your zoom in zoom out effect.
Reminder - any problems with that, and I will post a how to in your thread with screenshots.