Updating jsonb rows

this ...
DO
$BODY$
declare
j_final_rslt jsonb;
begin
select jsonb_agg(row_to_json(alias)) from
(select prompt_seq, attribute_name from tfinal_rslt limit 2) alias
into j_final_rslt;

raise notice 'j_final_rslt BEFORE %',j_final_rslt;
select jsonb_set(j_final_rslt, '{0,prompt_seq}','99',true) into
j_final_rslt;
raise notice 'j_final_rslt AFTER %',j_final_rslt;
end;
$BODY$

gives the result:
BEFORE [{"prompt_seq": *150*, "attribute_name": "InsuredTimeframe"},
{"prompt_seq": 1200, "attribute_name": "DriverOccupation"}]

AFTER [{"prompt_seq": *99*, "attribute_name": "InsuredTimeframe"},
{"prompt_seq": 1200, "attribute_name": "DriverOccupation"}]

How could I change this to ALSO change the attribute_name on the 2nd record
to "ABC". The AFTER result would ideally look like:

AFTER [{"prompt_seq": 99, "attribute_name": "InsuredTimeframe"},
{"prompt_seq": 1200, "attribute_name": "ABC"}]

tia, Mike