In GL, you only revalue foreign currency balances that are not settled yet.
The final exchange rate gain/loss is calculated when the balance is settled.
For example when the invoice is paid in AP and the receipt is entered in AR.
You run revaluation to temporarily produce exchange rate gain/loss entry so that income statement report displays true income. You immediately reverse these entries as of the beginning of next period.
You do not revalue all foreign currency accounts because they do not affect exchange rate gain/loss.
For example consider following transaction:

DEBIT: OFFICE SUPPLIES $120 USD ($110 USD)
CREDIT: CASH $120 USD ($110 USD)