Thanks for reaching out to us here in the Community, @teresa-tweetybea
At the moment, restricting a user to specific bank accounts isn't possible in QuickBooks Online (QBO). I know how this feature is useful on your end.
For now, it is best to put forward your suggestions through feedback to our product developer. They may consider your suggestion in our future updates. Here's how:
Select Settings ⚙, then Feedback.
Enter your comments or product suggestions. Then select Next to submit feedback.