[GNC] How to record currency exchange loss with Trading Account?

[Outlook]

Hi all,

I’m using multiple currency in latest GnuCash with Trading Account enabled.
After reading Peter Selinger’s articles, Tutorial on multiple currency accounting and Multiple currency accounting in GnuCash, I learned much more about Trading Account for multiple currency support.

Trading Account shows that I have currency exchange loss in 2020 and I want to record this loss as an entry before closing book.

The Trading Account is generated automatically by GnuCash and can not be modified.
How should I do the entry for the currency exchange loss with an income/expense account to make a balance for the Trading Account? This is for year 2020, and gains/loss will be recalculated for 2021 after balancing.

Thanks,
Thomas Chen