I try to accept an invitation from another resigned accountant however the system keeps asking me to "Sign up for QuickBooks Online Accountant", while I already have one.

I understand how important it is to flawlessly accept the accountant's invite, dancy-ddhtax-com. I'm here to help you get this resolved.

Since you already have a QuickBooks Online Accountant firm, please make sure the another accountant sent the invite to the correct email address. It should be the one tied to the user ID you use to sign in.

1. Open the invite email.
2. Select the Accept Invitation.
3. Sign in with your existing user ID and password.

If the error remains, please check if you have other QuickBooks companies open in browser windows or tabs. Then, sign out of them. After that, let's accept the invite again. I'll show you how:

1. Open the invite email.
2. Right-click the Accept Invitation link and copy the web address.
3. Open a new private web browser. In Google Chrome, this is called an Incognito Window. For other browsers, it's a Private Window or Private Browser.
4. Right-click the address bar and paste the copied web address.

This opens the sign-in page manually. Then, enter the user ID and password you use for your QuickBooks Online Accountant firm.

If none of these fixes the problem, I'd suggest asking another accountant to cancel the invite so that they can send a new one to you.

Here's how to cancel the invite:

1. Go to the Gear icon and then select Manage users.
2. Select the Accounting firms tab.
3. Look for your accountant firm.
4. In the Action column, select the small arrow icon and then click Delete. 

If they see any duplicate invites, I'd also suggest deleting those.

Once done, they can now send a new invite to you.

Additionally, I've included an article that'll help you learn about the special tools that you'll be using when working on a file. These tools will enhance your bookkeeping: Use Accountant Features.

I'm only a few clicks away if you need assistance accepting the invite, dancy-ddhtax-com. It's always my pleasure to help you out again.