Until then, I could only undo the specified layer, but I must have clicked something wrong and undo is not applied to the specified layer... To explain the situation, I left the layer I was first sketching on and sketched on another layer. And then I went back to the first layer. However, when I press the undo button because there is something to edit on the first layer, the undo is suddenly applied to the previous layer... What should I do to go back to the original state? Do I need to reset it... If I do it, will the pictures I'm currently drawing be lost...? The device I am using is an iPad. (ipad)