My Master Adm was one of my previous accountant but he left since then I couldn't exchange from him the Master Adm back. Need help to do it by Quickbooks.

It's nice to have you back here in the Community, @PuzzleCoffee.

I've got the actions that you can take in order to change the Master Admin of your account.

In this particular case where the Master Administrator has left the company, you'll need to call in to speak with a member of the Support Team. A representative will assist you by gathering the necessary info to complete a Master Admin claim. Once the claim is finished, the rights will be transferred to you or any other desired account user.

To reach them:

1. Click on Help at the top.
2. Hit on Contact Us.
3. Enter a brief description of the concern, which is to change the Master Admin in the How can we help you with box?.
4. Select on Let's talk.
5. Press on Start a chat.

Another way to change this is to submit a request to be the master admin. In this case, you'll be able to email us your request together with your supporting documents. 

To learn more on what are the information that needs to be gathered in this process and on how to perform it, this link got you covered: Learn how to become the master admin or primary contact for a QuickBooks account.

I'll be right here to lend a helping hand if you need anything else. Feel free to leave a reply below. Have a lovely day!