Hello @liz44,

In QuickBooks Online, the frequently accessed page resources stored on your browser may affect your browsing experience. They can cause unexpected browser problems like how your customers received an error while accessing the payment link on a sent invoice.

That said, let's consider letting them review and pay the invoice using a private or incognito browser so we can isolate this issue. Here are the shortcut keys you can provide for easy access:

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

If this works, you can continue letting them clear the regular browser's cache so the system can start fresh and improve their browsing experience. But if the same results show up while using a private browser, let them use a different browser app instead.

Additionally, I've also included this reference helpful with the steps needed on how you can personalize and add specific info to your sales forms: The Tools to Create Attractive, Professional-looking Invoices, Estimates, and Sales Receipts.

Don't hesitate to post again here if you have other questions or concerns with QuickBooks tasks and navigations. I'm always around happy to help. Take care and stay safe!