You can set the following preferences in the File References category of the Preferences window.
To return to the default factory settings, choose in this window. Note that this resets the preferences in every category in the Preferences window.
See File Referencing for information on referenced files.
Select to allow editing of animation curves from referenced files. See Edit animation curves from referenced files.
Select to allow locking and unlocking of attribute values from referenced files. See Lock the value of an attribute.