How do I turn off those annoying suggestions on every page that are trying to get me to setup QuickBooks Payments, or American Express or some other add-on I don't want?

Welcome to the Community, Mike.

I can see how an option to turn off suggestions could be helpful for you. However, this feature is currently unavailable in QuickBooks Online. 

The good thing is that QuickBooks acknowledges feedback and suggestions from customers like you to help us improve our products and services to make your experience with us even better. 

Here's how:

1. Go to the Gear icon, located at the top right corner.
2. Select Feedback.
3. Enter your suggestions/comments and click Submit.

Your feedback will be highly appreciated. You can also track the status of your request in our customer Feedback for QuickBooks Online. 

I also recommend visiting our QuickBooks Blog to stay up-to-date with our latest news, information about our new feature, and recent updates. 

Feel free to reach out again if you have more QuickBooks concerns. Stay safe.