How can one show the foreign currency balance in a foreign currency bank account account?

Let's go to the Chart of Accounts tab to locate the balance of your foreign currency bank account, @stefan.zehle. I'd be glad to guide you how. 

1. Go to Accounting from the left menu. 
2. Select Chart of Accounts.
3. Find your foreign currency bank account. 
4. View the balance in the QuickBooks Balance or Bank Balance column. 

The screenshot below shows you the steps. For more details, see the Track account currencies and balances section through this article: Adding A Foreign Currency Account. 

Moreover, you can run the Account QuickReport to view the transactions associated with that account. Just click the Account history drop-down from the Action column. Then, choose Run report as seen in the screenshot below. 

I'm here anytime you have other concerns. Enjoy the rest of your day, @stefan.zehle.