I am trying to make a 2d animation in blender and appreciate the grease pencil tools. However, I find it hard to say keep a tree in the background for multiple frames. Is there a way to make one layer remain constant when adding new frames? I have tried locking the layer, but that in turn locks everything which I don't want. If I want a guy to walk in to a city, I want the landscape locked, but the character himself not. How should I go about doing this? Thanks so much.