Changing the owner of multiple documents can only be done in the Documents Control Panel.
Add the required documents to the Clipboard by ticking the checkbox to the right of the document name and clicking Clipboard. Once loaded into the Clipboard, click Change owner.
Assign a new owner and click Change.
It is possible to add a folder to the Clipboard and then tick the "Including all child objects" checkbox before clicking Change. This will change the owner of the parent folder added to the Clipboard, and all subfolders and documents within.