If you are looking for a particular string within a GPO, but you don’t know the gpo? Here is a good way to search group-policy for that string, and get the GUID for you.

cd \\contoso.com\sysvol\contoso.com\policies
$gpos = get-childitem -recurse | select-string -pattern "string" | group path | select name
foreach ($line in $gpos)
  select-string -inputobject $line -pattern "(?<=\\\{)(.*?)(?=\})" | select matches

That will grab you the GPO GUID. You can then pipe that into a “get-gpo” to find which gpo contains your string.

Further on from this, you can then do a ‘find-and-replace’ to automagically replace the string within your GPO.