Score variable starts from 0 every time i open the screen

I am using a variable for countring score points. When the screen starts it has 0 points. For every correct answer gives 5 points and then it saves the value in realtime DB. When you leave and reenter the screen it shows the last value of score BUT when i enter a correct answer it doesnt go for example from 70 (last value saved) to 75 points but again from 0.

Any suggestions?