Assuming these are management fees on rent receipts, then the best way is to reverse each of the transactions from last month that were incorrect, and re-enter them this month with the correct fee % set on the property.
However, this does show on the tenant's record and currently these cannot be hidden on a tenant's report.
So if there are 3 or more, the next best way would be to raise a new Admin fees charge for the difference. If this is negative, then this could leave the Admin Fees Ledger in overdraft, especially if they do not generally raise Charge Admin Fee transactions.
The third most preferred way is to use Payment Ledger Transactions out of the Management Fees Ledger AND out of the GST Ledger, followed by Receipt Owner transactions into the owner account. This method requires separate ledger payment entries for the fee and GST in order to keep the GST figure in line with the other fees collected, BUT this method will not alter any statistics reports on fees collected - the other methods will.