How to amend historical rate type

Summary

Historical Rate is being automatically generated by system using the Period Average

Content

We are posting a series of journals in our USD ledger, the journal is being posted in GBP using the month end corporate rate.When we run the translation balances and run the Smartview TB in GBP the GBP balance does not tie back to the original GBP journal posted. Upon investigation Oracle is automatically generating the historical rate using the  Period Average, we want it to be generated to take the Period End rate. 

We want to avoid manually amending the rate each month, is there a configuration setting where we can amend this just for this particular GL Account?