Hey there, Nolstev.

Allow me to take over and help you change the account detail type via QuickBooks Online.

To better isolate the issue, you may want to unlink the sub-accounts and make them inactive for the meantime. After that, try to change the account type again. If none of these steps work, let's run some basic troubleshooting steps to isolate the problem. We can start by accessing QuickBooks Online in a private browser. This usually resolves any browser-related issues.

Here's how to open a private window in different browsers:

• Google Chrome: press Ctrl + Shift + N.
• Mozilla Firefox: press Ctrl + Shift + P.
• Internet Explorer: press Ctrl + Shift + P.
• Safari: press Command + Shift + N.

If you're able to change the account type via the private browser, let's go back to your regular browser and clear its cache.

However, if the problem persists, I'd suggest reaching out to our QuickBooks Online Support. Agents have the necessary tools, like screen-sharing to get you back up and running. 

You may find this article helpful: https://quickbooks.intuit.com/community/Help-Articles/How-to-change-the-type-of-an-existing-parent-a....

Let me know how it goes so I can look further into this. I want to make sure you'll be able to change the account type.