searchpath reverts to default after each server restart

When i run the command
SET search_path TO custom,idsystems, clientdata, configs, replication,
structure, archive;
then when I run
SHOW search_path;
it does show those schemas as the search_path. however when i restart the
postgresql service, the search_path has reverted to $User, public.
when i put the SET search_path function in the postgresql.conf file (as
below) the service wouldn't restart. i think because it doesn't like the
"public" schema (which i don't use).

#[postgresql.conf file:]
# the postgresql service wouldn't start with this setting.


# CLIENT CONNECTION DEFAULTS
#---------------------------------------------------------------------------
---

# - Statement Behavior -

search_path =
custom,idsystems,clientdata,configs,replication,structure,archive,public;
#schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only