Problem with candle-lighting and havdalah times in Jerusalem, Israel

You seem to be using a different sunset time for Jerusalem, Israel, than is commonly used here. 

I assume the difference is between observed sunset and astronomical sunset. 

1.  Can you make this an option in the future?  

2.  I tried to adjust for this by changing the offsets in minutes for candle-lighting and havdalah.  This works more or less for havdalah.  However, when I change the number of minutes before sunset for candle-lighting, your web-site changes the value back to 40.  Can you disable this annoying feature? 

Thank you.