How do I reinstate billing for a client I accidentally trensferred to client?

Hello there, @tricia29.

To transfer the bill back to your client, we need a to have a master admin permission. We can work together on how to change your client's access. I'm here to guide you.

QuickBooks Online allows you to add users who assist with bookkeeping for your business. You can grant each user-specific permissions to perform specific tasks. 

Here's how to add or edit QuickBooks users.

1. Choose Settings.
2. Choose Manage users.
3. Locate the user you want to change. Then, in the Action column, choose Edit.
4. You can alter the User type.
5. Choose which user settings you want to manage.
6. Select Save.
7. Ask the user to sign out and sign in again into QuickBooks Online to see the updates.

Feel free to visit this article for more information: manage users in QuickBooks Online.

Additionally, you can manage their roles and limit their access to a specific task. Check this article for your guide: User roles and access rights in QuickBooks Online.

If you require additional assistance with this topic, please visit the Community. I'll be there to help you. Have a wonderful day.