If you think someone else may be accessing your Facebook account without your consent or you logged in to a different device and forgot to log out you can try to remotely log out your Facebook account from other devices.
You can do this on Facebook by following the following URL: https://bit.ly/2uSWuQM
There, right beneath the title, you will be able to choose the platform you are referring to (Computer or Mobile). Select the correct one for the platform you are using, the steps recommended will be different.
After doing this you can also visit the following page so you know how to keep your Facebook account secure: https://bit.ly/2qarN3Q
Please note that we have no access to your Facebook login information and if your account is linked to Facebook and you feel is not secure, this is something we cannot assist with due to this reason.
For any issues related to your Facebook account login please contact Facebook directly so they may assist you with the matter as they have all the information regarding your Facebook account: https://www.facebook.com/help/