On the fly calculations on Edit page

Hi,
In my program i calculation lots of values on the fly as maintained in following tutorial along with Relational drop down menus.

https://xlinesoft.com/phprunner/docs/how_to_calculate_values_on_the_fly.htm
All Working fine, But...

1. When i goto edit page. It needs to be calculating on the fly again if we need to change some value.
   
2. Drop down value should be same as entered, it somehow resets it self.
   Please help.
   Thanks