We appreciate the hurdle you've done on handling payments and/or invoices in QuickBooks Online, @brandanbruce. I'm here to help you sort things out.

Excessive historical data kept in your browser might cause problems like these. I advise performing some basic troubleshooting procedures to see whether your problem is browser-related.
 

Start by logging into your QBO company using an incognito browser. Here's how:

• Chrome: Ctrl+Shift+N
• Firefox: Ctrl+Shift+P
• Safari: Command+Shift+N

If this works, I recommend clearing the regular browser cache. This will avoid the browser to behave strangely. Otherwise, kindly use another supported browser. 

For future reference, see this article about making some edits on sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Keep us updated by leaving a message below. We'll do our best to reply quickly if you have other concerns about this or QuickBooks. Take care!