When you click + icon in the frame animation panel the frame that get added is the composite of the layers visible in the Layers Palette. Change the visibility of layers in the layer palette to change the content of the frame added. You can height any frame in the panel and change its content by changing which layers will make its composite image. You can also change layer position, opacity and effects in frames. This animation has two layer the top one has a layer mask to mask the lower layer clouds and the top layer content is not linked to the mask. So when the top layer JJMack content is moved the logo is mask for the lower layer clouds. I moved the upper layer content is the second new frame added and had tween add frames between the first and second frame. Both layers are visible in all frames.