Welcome back, Desiree 869. :)

Fiat Lux has got you off to a great start as they're right, in order to be able to have a vendor that uses US currency, they'll need to be set up for US currency. Creating a backup before moving forward is also a great suggestion. I'd like to fill in a few more details to make sure you have the information you need.

Once you set up a vendor, customer, or any other item in QuickBooks Desktop with a currency, that currency cannot be changed. If you have a profile set up for this vendor already that's in CAD, you'll need to create another vendor profile for them and choose USD as the currency. You'll need to change the vendor name slightly in order to do this. In can be as simple as adding a period to the end of the name.

Since you already have transactions with this CAD vendor, I recommend deleting the existing transactions and re-entering them with the proper vendor and currency as there isn't a way to switch it.

One other thing I'd like to highlight is that products and services in QuickBooks Desktop can only be set up with the home currency. Meaning, if you're hoping to have your products purchased from this vendor reflect the cost they're charging you, you'll need to manually calculate the conversion rate yourself and enter that as the cost on the item.

You can learn more about multicurrency in QuickBooks Desktop here: Set up and use Multicurrency

I'm available if you have more questions!