In the chart of accounts I can not create the bank account in USD

We don't want you to experience this, Rucy. Let me help you resolve the issue with multicurrency in your chart of accounts when you create a bank account using USD currency in QuickBooks Online (QBO).

The first thing I can suggest is to refresh your browser. If the issue persists, open your browser's private window. It allows you to isolate the cache, which is the common cause of unusual behaviors.

Here are the shortcut keys:

• Mozilla Firefox and Microsoft Edge: Press Ctrl + Shift + N
• Google Chrome: Press Ctrl + Shift + N
• Safari: Press Command + Shift + N

If that works, return to your regular browser and clear its cache. Otherwise, open an alternative browser that's available for you. 

For more information, you visit this article: How to add a foreign currency account in QuickBooks Online.

On the other hand, consider scanning this article for future help that can help you get FAQs about Multi-currency in QBO: Common questions about using multi-currency in QuickBooks Online.

Don't hesitate to click the Reply button if you have additional questions when adding multiple currencies or other related concerns in QuickBooks Online. I'm more than willing to help.