Bonjour

The new Yahoo Mail app is completely insecure.

In fact, a hacker has taken control of my email account, and I can't log out.

I have no way to log out in the new Yahoo Mail app.

Therefore, anyone can access my email without even a password.
With the old app, I could log out through the "Help" menu.
Could you please tell me what steps I need to take to fix this critical problem?
Thank you so much for your help.