If I can have 3 users and 2 accounting firms, when I added my second accountant now the orginal firm cannot log back in. What happened?

Hello there, kmccartha,

You can add two accounting firms in your QuickBooks Online account. You can let them check if their login credentials are correct. That might be the reason why they're unable to log in.

If the login credentials are correct, let them perform browser troubleshooting steps to rule out any browser-related issues. Log in to QBO in an incognito or private browser. This mode will not save any browsing history.

Here are the keyboard shortcuts: 

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

If they're able to log in successfully, open the regular browser again and clear its cache. Please make sure to close and re-open the browser afterward. Alternatively, try using a different supported browser.

Let me know if you have other questions.