"copy" you can find: Tool bar Category <Edit>. The button (Icon) "copy" you can find: Tool bar Category <Edit>.
Mark the area which you want to copy. The marked (selected) area can go over several staves and voices. Then click on the corresponding button (Icon):
After copying, all highlighted notes and rests included all associated symbols will be copied to the clipboard. With Paste you can insert the copied content in an arbitrary place.
You can use alternatively |Ctrl | + |C
Also, you can mark and copy Symbols