I am using Quickbooks Online Accountant.

I have discovered how to do this. A particularly helpful QB consultant (online help) called Giedre advised as follows:

Head to : Settings ⚙.

>Select Currencies.

> choose the currency that has issue on balance sheet

> click on drop-down on the right side

> choose revalue currency

> choose which accounts needs to be revalued

> save it

> run ''balance sheet report'' to check it worked and review balance on bank transactions register (they should be the same)

When I did this QB suggested both the bank account with the issue and the currency's creditors account.  For the exercise I was doing, I just chose the bank account.  I did as suggested and the problem was taken care of.