Welcome to the Community, @kathy13. Allow me to help you with changing the Master Admin on your account.

Here's how the Master Administrator when logged into QuickBooks Online can transfer right to an existing Company Administrator: 

1. Click the Gear icon.
2. Select Manage Users.
3. Click the drop-down arrow in the Action column and choose Make master admin.
4. Select Make master admin on the pop-up that appears.
5. An invitation email will then be sent to the user to accept the role. 

I recommend the following article for additional information on this process, such as the basics of transferring this role: How to Transfer The Role of Master Administrator.

Should you have any questions about transferring roles or anything else, I'm just a click away. Cheering you to continued success.