When you are building or editing your ads in “single view” you can see all layers added on the bottom of the screen. It might happen that the layers you have added in a slide don’t necessarily enter from the very beginning; however, you see them present on the canvas and overlapping with other layers, like in the image below:
That is actually the expected behaviour. The ad editor will always show all layers of the slide placed in the canvas. If needed you can hide them to have a clearer view and keep on working on the design.
Note that the overview on the stage is not how your ads will render when they are live. In that scenario, layers will enter just at the time you’ve chosen, with no elements overlapping with each other.
Even if the overlapping of layers in the stage doesn’t affect the end result, you still want to avoid that from happening, we would highly recommend making use of Slides in your design and building the different frames. That is the only way to prevent the behaviour described above.
We hope the information above solved your question. If there is anything else we can help you with, and you couldn't find it in our help center, don't hesitate to contact us by chat. We are always ready to help you!