Solve a problem in iPhone and Android app. Read project description before bidding.

*Please read project description carefully before bidding* Hello Freelancers, I already have a completely developed Android and iPhone application. I want a change in both the apps. -> This app uses Facebook login. When a user signs up in the app everything is working well. But this same user logs in with this same facebook account in another phone(android or iphone) then this account is created as new one. Like, suppose if X is the user and X logs in in Phone A it's all good and when X logs in with Phone B then this is created as new user in the database. So the problem here is if the user changes his profile picture, name, age, phone number etc in Phone A then it is not reflecting in Phone B and vice versa. The problem is clearly explained here. Please bid only you think you can complete this project. There are two more minor changes which are very easy for the one who can solve the above problem. Problem:- The app has guest user which is like no login required but it stores the user information in the server(PHP code) and it remembers the phone with a unique id. I think this is making the app to create duplicate facebook accounts in the database. Skills required to apply for the project:- VPS knowledge must, Swift, Android, PHP, Facebook Login integration. The other two small works are 1. Upload backend part to the VPS(currently files are in other VPS which is not mine) and connect this VPS in the app. 2. Change Facebook account to new one. I cannot afford much please bid accordingly. Credits will be given to the freelancer on the website. Thank you so much.