You need to set up the layers before making the frame animation. If the movement is constant, then you can do it with a single layer, and use Tweening. If the object changes size, or rotates or similar, then you might be able to use Free Transform Step & Repeat.
The layer order is not relevant, although it makes life easier. You just need the right layer to be turned on for any particular frame.
Edit: Also, when scrubbing through the timeline, is it possible to hear the audio track? This project requires a text crawl (where the text moves upwards vertically in the frame) in sync with a voiceover, which is reading from the text. Unfortunately, the voiceover was recorded BEFORE the animation was created. So I need to sync the text transformation to the VO.
To be clear, I simply have a title (text) crawl -like a credits sequence- being read in a VO. So the the text & VO need to be in sync.
I don't believe it is possible to hear the audio track while scrubbing in Photoshop. It is usual to sync visually from the peaks in the Audio waveform, but Photoshop does not allow us to view the waveform either. Perhaps another app would make life easier? I use Premier Pro on a Windows system, so don't know about the alternatives — especially free ones, but I believe there are options out there.
I was able to create the text crawl, but it's out of sync with the audio. But the animation is exactly what I had planned.
So I guess the best thing now is to import the animation -without the audio, to premiere pro. Then re-import the audio, & try to adjust the video clip to the audio in the timeline.