Foreign Currency journals copying from primary to secondary ledger

I have created a foreign currency journal in primary ledger from GBP to USD with exchange rate 0.85 on 01-Aug-21 when i try to copy the data from primary ledger to secondary ledger on a different date/time the rates are updated so in this case the rate is 0.87 at time of copying the data from primary to secondary.

Can you please advise which rate will be considered to copy the journal data from primary to secondary? Also if it considers to copy the data with rate on the copying date, i don't want that, i want original rate at the time of copy when the journal was booked in primary, how to restrict this?