When you've selected an XRef object in a scene, the XRef Object rollout appears along with the Proxy Object rollout on the Modify panel. The modifier stack for the XRef object simply displays “XRef Object.”

These controls let you change the file path, file name, and object name of the source of the XRef object.
Highlight Corresponding XRef Record in the XRef Objects DialogClick to open the XRef Objects dialog, with the selected object's record highlighted.
Path button
Path buttonClick to display the XRef Merge dialog pointing to the scene in the XRef File Name field. Here, you can specify a different object to be used as the XRef object.