Simple Instructions:
To update the value of a piece of metadata, first choose the file to which that
value applies, and then the metadata element whose value you want to change.
Your selection appears in the metadata edit controls. Edit the value field and
click "Replace" to alter the metadata.
The process is the same when updating a folder with child folders or multiple
files, except that when you click "Replace" you are asked what to do with the
other files. The buttons offer different options: "Replace" replaces any
previous value with the new one; "Replace All" adds the new value in the same
way to all other files; "Skip File" skips the current file and proceeds to the
next; "Cancel" undoes any changes and cancels the action. You can only update
metadata that is common to all files selected. For a folder, this means that
all its contents must share the same metadata.
The value tree shows all previous values, not just those currently assigned.
Thus the value you have replaced will remain in the value tree.