It's nice to see you here, @Frances15NBS,
You've got the right support page to help you with your journal entry concern. I'm here to share some insights about the error you're getting and the options to resolve it.
QuickBooks Online will block journal entries with multiple currencies for customers or suppliers. Doing so may lead to incorrect open balances or incorrect exchange gains or losses in your books.
The error comes up when the system detects a journal entry that includes accounts receivable (A/R) or accounts payable (A/P), that doesn't match with the customers/suppliers the A/R an A/P accounts.
All customer or supplier transactions must be recorded in the currency assigned to them.
But don't worry, you can simply create a separate journal entry for each currency so you can avoid this error message. I also found this article with the steps on how to resolve the error message. See it here: Multi-Currency: Journal Entry Error Message
That linked article is for QuickBooks International, but the steps will work with the US versions.
Kindly update me on how everything goes. I'll be right here to share some more insights about your journal entries. Have a good one!
