Hello, @qiyanqi. I'm here to assist you in re-adding your clients to QuickBooks Online Accountant.
To do this, ask your client to send the invite to the email address associated with your QuickBooks Online Accountant firm. They can follow these steps:
Sign in to QuickBooks Online as a primary admin.
Go to Settings ⚙️ icon and select Manage users.
Click Accounting firms.
Enter the accountant's email address, then select Invite. Follow the prompt to verify your account.
Once this is done, open the invite email and select the Accept Invitation link. Then, sign in with your user ID and password. When you accept the invite, QuickBooks will connect their accounts to your firm and add them to your client list, allowing you to review and make edits to their books.
Please note that the steps above are intended for clients who already have QuickBooks. To add clients who are new to QuickBooks or if you want to add them to your ProAdvisor Preferred Pricing plan, you can follow the steps in this article instead: Add clients to QuickBooks Online Accountant.