Hi there, particle06.

Welcome to QuickBooks Community. I'll share troubleshooting steps on how to fix unusual behavior in QuickBooks Online.

Can you please provide the specific error message you encountered when trying to edit the customer's information or make them inactive? I appreciate any extra details so I can present accurate information.

In the meantime, I recommend logging in to your QuickBooks account using a private browser. Then, access the Customer's center from there, to rule out the possibility of a webpage issue since private browsing doesn't store local files or cache.

Use these keyboard shortcuts based on the browser you're using.

• For Firefox or Microsoft Edge, press Ctrl + Shift + P.
• For Chrome, press Ctrl + Shift + N.
• For Safari, hold down Command + Shift + N.

If it works in incognito, I recommend clearing the cache of your regular browser. This removes the history or log of sites so you can start with a clean slate. You can check this article to see the steps: Clear cache and cookies to fix issues when using QuickBooks Online.

If the steps above didn't work, use another supported browser as alternatives.

You can refer to this article to see additional steps on how you can make a customer inactive and make them active again: Make a customer inactive and then active.

Please refer to this article to see details of how the Sales page gives you a great at-a-glance view of the status of sales transactions, open invoices, and paid invoices: View sales transactions. You can also view, create, and edit sales transactions from within that page.

Please let me know how this works. I'll be happy to help you further or if you have any other questions about QuickBooks. Have a great day ahead.