Good calculator Terrible graphing

I have used this calculator for graphing purposes mainly. Even when I reset the calculator and change the setting for example parametrics. Sometimes I doesnt even show the graph and it is not accurate that for sure. When I work on the real TI-83 it works fine and causes me no problems please fix this its a great app besides that huge flaw. I have an iPhone 6 by the way.

M.Amar about GraphNCalc83