Can't apply payment or click into details of an invoice. tried multiple PC's and multiple users. same results. is there a setting somewhere that is incorrect?

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!

Hi Mitch - I have tried multiple users, multiple Browers and multiple PC's.  We can't apply payments or click into invoice details more than once per login.  I can open a private browser and operate normally.  We have cleared the cache multiple times on 3 different browsers.   any ideas on how to correct the issue?

Hello, brandanbruce.

Thank you for taking the time to follow the steps outlined above by my colleague Mich_S and tying it together on multiple computers. This should work after clearing your cache since it works normally when you open or tries it in a private browser.

This issue requires further investigation; I recommend contacting QuickBooks Online Support. They have the tools to open your account and submit a ticket to investigate the actual cause of this problem.

Here's how:

1. Sign in to your QuickBooks Online company.
2. Select Help (?).
3. Click Talk to a human.
4. Enter your concern.
5. Select Contact Us.
6. Choose a way to connect either Chat with us or Have us call you.

I've also added this article about fixing an invoice payment applied to the wrong invoices for future reference: Fix a payment applied to the wrong invoice in QuickBooks Online.

You're welcome to post again if you need anything else. We're happy to help you.