Search and replace is only available in Bulk Mode.
be going at this the wrong way.
what are you trying to fix?
Authors (any single name), Publishers, Tags can all be renamed (if the new name exists, they will combine with the others) via the Tag Browser and/or Manage button at the bottom. This fixes all occurrences.
S&R is useful for removing other extraneous stuff from a field (eg Series included with Author)