Hello,
Thank you for reaching out to LastPass support, my name is Hilda and I will be assisting you with the issue you're experiencing.
Usually this behavior is experience when you access LastPass using the web (lastpass.com) and your master password is store locally in your browser, your browser will detect all password fields and will automatically fill them with or replace them with your master password. To prevent this from happening, remove the store master password from your browser or disable autofill. In addition to that, do the following troubleshooting:
Have a good day!
Hilda
The LastPass Support Team
Please visit our support center athttps://support.lastpass.comto access our knowledge base or to contact our Customer Care team.