Copying All Settings Of One Composition in AE I want to copy the whole settings of the composition to the other, all keyframes, transition points, 3d layer etc. In Adobe After Effects
This is not possible to do in one step, it is only possible to duplicate compositions:


Select the composition (Import Footage Panel)
Press Ctrl+D (or go to Composition > Duplicate Composition)
As (almost) everywhere in AE, hit Enter on the selected composition to rename the duplicate




When you need to copy the properties of a layer:


Select the Layer
Click on the tiny Triangle > left beside the layers name to open up the properties
Select Transform, Effects or Mask
Press Ctrl+C
Switch to the Second Composition
Select the Layer
Set the playhead to the animation start frame (first keyframe)   
Press Ctrl+V to overwrite all properties and insert all copied keyframes


To check the result, press U on the Layer, this will open up all animated properties of the layer. 

Note: Copying the same properties of different layers is also possible by selecting multiple layers, open up the properties simultaneously, and select them by holding down Ctrl or Shift. 



Related: After Effects: Shortcut for showing all transforming properties of a layer