Can anyone explain why when I go to Accounts and Settings then to Sales Tab, at the bottom of the screen I click on the Statements category to edit it and it disappears?

I appreciate you taking the time to elaborate on your concern and performing prior steps, @sam-urbanconstru. 

Upon checking, I've found an ongoing investigation (INV-97234) about the inability to modify and save the changes to the statement settings in QuickBooks Online (QBO). No worries, our development engineers are currently working to find a permanent fix.

With this, I recommend reaching out again to our support team to have your name listed on the affected users, if you haven't. This way, you'll receive timely email updates. 

Here's how:

1. Log in to your account.
2. Select Help (?) then click Contact Us
3. Choose a way to connect with us:

• Start a chat with a support expert.
• Get a callback from the next available expert.

In the meantime, feel free to visit this article to save you time in the future when your customers pay for products or services:  Create sales receipts in QuickBooks Online.

I'll keep an eye out for your response in the comment section should you have more customizing and QuickBooks-related inquiries. We're available for you 24/7.