You can use the unrealized foreign exchange gain and lose feature to revalue your foreign asset and liabilities.
Go to GL menu, Unrealized Foreign Exchange Gains and Losses
Assuming your home currency is in CAD.
You would choose the Include Foreign Currency Assets option only and then enter the correct exchange rate to convert your USD bank balance into CAD .
For example, if your balance is $1000 USD and its current value in CAD is $1200 and you want to adjust it to be $1300 CAD. You would enter the exchange rate as 1.3.
Click on create draft transaction, and you will see the system debit and credit the same account with 1 USD which would result in USD balance being untouched but there is a large multiplier used that would adjust the CAD balance. The transaction would also contain other foreign assets. If you do not want to revalue such assets, you can delete lines to revalue other assets from the draft transaction.
Once you are happy with the end result, you can post the transaction into the GL.