Highlight a library/vol, click Add Copies (top bar, not Actions), the default circ library is the selected library. But if clicking Actions -> Add -> Copies, the default circ library is the workstation library.
Highlight a library/vol, click Add Copies (top bar, not Actions), the default circ library is the selected library. But if clicking Actions -> Add -> Copies, the default circ library is the workstation library.