In array i have to update data to specific column tried using update array function

[ld_id=1188, ll_id=904, fl_id=, fm_id=, rsed_id=, appian_document_id=5357264, klt_id=, legacy_id=, description=, name=, createdby=testc, createdon=10/3/2022 7:14 PM, modifiedby=tects, modifiedon=10/3/2022 7:44 PM, inuse=1],[ld_id=, ll_id=904, fl_id=, fm_id=, rsed_id=, appian_document_id=6057969, klt_id=, legacy_lease_id=, description=The Parties, by mutual agreement, due to the Partial Surrender of the Demised Premises, agree to amend items 1 ("Base Rent"), 3 ("Demised Premises") and 10 ("Shared Property Expenses") of the Summary of Terms and Definitions of the Agreement., name=, createdby=testc, createdon=10/3/2022 7:44 PM, modifiedby=, modifiedon=, inuse=1],[ld_id=, ll_id=, fl_id=, fm_id=, rsed_id=, appian_document_id=6057968, klt_id=, legacy_id=, description=, name=, createdby=, createdon=, modifiedby=lecst, modifiedon=10/3/2022 7:44 PM, inuse=0]

This was the pv variable cdt data in that for second id (second occurence) means where document id =6057969 i want to update "description" column data i used update array function in the place of index i was confused what exactly needs to be provided kindly suggest on this

updatearray(
array:pv!documentsToUpdateInDB,
index:index(
pv!documentsToUpdateInDB,
*tried with many ways here by passing as index not worked*
),
value:"The Parties, by mutual agreement, due to the Partial Surrender of the Demised Premises"
)