When viewing documents uploaded through the Google Services Integration, documents are previewed as PDFs in the Google Services Integration Viewer. This viewer previews documents in a read-only state, and a lock is not placed on the document unless you switch to an alternate viewer.
If you do not want to view documents as PDFs in the Google Services Integration Viewer, documents can instead be opened in a Microsoft Office document's native Microsoft Office application or in the Unity Client Embedded Viewer. To view documents using an alternate viewer, see Opening Documents in an Alternate Viewer.