Downloading bank statements in QBO format - it won't let me. Asks "which account are these transactions from" it then has quickbooks drop down menu - can't pick anything

Welcome to the Community, @purpleaallegra. 

Allow me to provide an alternative solution for you to download bank statements in QBO. That said, I'd recommend logging your account through a private window using these shortcuts: 

• Mozilla Firefox: CTRL + Shift + P
• Microsoft Edge: CTRL + Shift + N
• Google Chrome: CTRL + Shift + N
• Safari: Command + Shift + N

 If it'll work, the cause must be from your regular browser. However, if the issue persists, you'll want to clear cache and try logging in another supported browser. 

Additionally, check this article which will help you if you want to review downloaded bank and credit card transactions in QBO: Categorize online bank transactions in QuickBooks Online.

I'll be here to help should you have additional assistance needed regarding your banking transactions. Keep safe.