When you copy/paste from one drawing to another several things happen that you need to keep in mind.

1. Handles. If you set a handle on an object before copying it, when it is pasted into a new drawing the same handle will be set. You can use this to paste the object precisely where you want it in the second drawing.

2. The layer order will be preserved, but the layer names and properties are not transferred. So, if an object is on layer X in the first drawing it will paste into the second drawing on layer X. The pasted object will assume the properties of the layer in the new drawing (if any have been assigned).

If Layer X is not visible in the second drawing the object will be pasted anyway, but it will not be visible. However, the big blue dot handle will be visible.

The object will be selected after it is pasted. If you click the "A+" button in the "Layers Toolbox" immediately after pasting (while the object is still selected) the object will be moved to the active layer of the second drawing.

If you select everything from one drawing and copy/paste to a new drawing the layer names (and other layer properties) will not be transferred to the new drawing.

3. Scale. You can set units for a drawing (inches, millimeters, etc.) but the program defaults to no defined units (Unit less). In fact, it uses "drawing units" in drawings that have no defined units. If units have been defined the left-most box on the right side of the "Status Bar" at the bottom of the screen will show the units ("in" for inches, "mm" for millimeters, etc.). If no units have been assigned (the default) the box will say "Unitless."

Objects in the first drawing will be scaled appropriately in the second drawing IF you have defined units in both drawings. So if an object is 1 inch long in the first drawing (where units are defined as inches) and you paste it into a drawing with units defined as millimeters, the pasted object will be 25.4 millimeters long.

However, if the first file does not have defined units, when an object is copy/pasted it will come into the second drawing using the units of that drawing (if units are defined). So an object that is 1 drawing unit long in the first drawing will be pasted in as 1 inch long if the drawing units are inches, or one millimeter long if the units are millimeters, etc.

If neither drawing has defined units the pasted object will the the same number of drawing units in both drawings.