Click Settings and Privacy - Privacy Checkup - How to keep your account secure. Step through the options, which starts with changing your password. There will be a review recent activity option. After that, change the passwords on all the e-mails on your account. It sound like somebody got in through a logged in session, as they didn't change your password. Facebook requires a password to make account access changes. Watch your activity and make sure that doesn't happen again. You could add two-factor authentication to your account. Go to security, login, add 2FA. In another window open 2fa.live (website). Paste the key phrase generated by facebook into the box at 2fa.live . Click "submit." The lower box will have the 6-digit code at the end of the key phrase. SAVE the key phrase!!!! Otherwise you have to go through a submitting ID process to regain access to your account. After that, when you login, you enter your password, then facebook will ask for the 2FA code. Paste your key phrase (that you save) into 2fa.live and enter the code returned. There are also 2FA apps you can use instead of 2fa.live .