Part B 

Follow These Steps :

Step 1 : Verify your Mobile Number

Open your mobile settings https://www.facebook.com/settings?tab=mobile and add/verify your mobile number

Step 2 : Active Login Notifications

Link : https://www.facebook.com/settings?tab=security&section=notifications&view

Step 3 : Active Login Approvals

Link : https://www.facebook.com/settings?tab=security&section=approvals&view

Step 4 : Add Three Trusted Contacts

Trusted contacts are friends you can reach out to if you ever need help getting into your Facebook account (ex: you forget your Facebook password and can’t get into your email account to reset it).

After you set up trusted contacts, next time you can't get into your account your trusted contacts can access special, one-time security codes from Facebook via a URL. You can then call your friends to get the security codes and use those codes to access your account. Choose 3-5 friends and confirm your choices .

Step 5 : I recommend you removing all trusted browsers after doing the above steps

Once you login from strange PC , you will be ask to enter a security code where you receive to your mobile as SMS, after that facebook will ask you weather to save your browser or not, once you save it facebook will never ask for another security code again. 

Link : https://www.facebook.com/settings?tab=security&section=devices&view

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