This isn't the type of experience that we want you to have when using the new invoice layout, gab. I acknowledge the effort you'll need to exert to navigate through this due to the transition to the new layout. 

You're right that through the new changes, customers may take some time to navigate and locate the other features that were effortlessly navigated previously. To address each of your concerns, I'll explain thoroughly so you can change tax rates, add customers without adding an address, and add an item seamlessly.

First and foremost, we can perform browser troubleshooting that resets your browsers to run flawlessly. It is also used to fix any browser-related issues when using QuickBooks Online (QBO).

To start, please use the following keyboard shortcuts for your respective browser:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Safari: press Command + Shift + N

From there, access your company file. Then, add your customers as how you want them to be set up, and enter a product item when creating an invoice. After that, it is recommended to clear your browser's cache or cookies to avoid similar issues in the future. Alternatively, opting for one of the browsers that are supported can also be a wise decision.

To change your tax rate, you can  run through the steps below:

1. In the Invoice transaction, go under the Subtotal and Sales Tax amounts.
2. Click the See the math hyperlink to route you in choosing a Sales tax rate.
   
3. Choose from the dropdown.
4. Then, hit the Close button.
   

Furthermore, you can check out this article to see how you can record an invoice payment once your client pays their statement of charges: Record an invoice payment. 

Let me know if you have additional questions concerning product preferences or creating any transactions within the application. The Community is available 24/7 to help. Take care!