Someone unauthorized is accessing my account. How do I prevent this and can I find out who is doing this?

Can I ask how it is that you know they are accessing your account?  

What signs are they leaving? 

Thanks for reaching out to the Community, Fhauth1.
 

If your account's being accessed by someone who shouldn't have access to it, I'd initially recommend changing the password used to sign in to it. This way, they won't be able to use your login credentials anymore.
 

Here's how to change an Intuit Account's password:
 

1. Use the Profile icon next to your Gear icon, then click Manage your Intuit Account.
   
   
    
2. In the Intuit Account Manager, go to Sign in & security.
3. Access your Password section.
4. Make the necessary changes.
5. Select Save.

From your Intuit Account Manager screen, you can also make changes to other sign in details, like the user ID, email address, and contact information.
 

I'd also recommend reviewing our security checklist in the Intuit Security Center. This has detailed information on how to best protect your books and private data from unauthorized access.
 

Please don't hesitate to send a reply if there's any additional questions. Have an awesome Wednesday!