I agree with [MENTION=3026]alcjphil[/MENTION] and [MENTION=61707]squirtdad[/MENTION].

Changing out the components to flat bars will require new brake levers & shifters, and will get pretty expensive if you pay a shop to do it. Drop bars and flat bars have different diameters, so the controls from one can't physically be mounted on the other.

I recommend that you try raising the existing handlebars with a riser stem or a steerer extender, or a combination of both.
Raise the bars so that the tops of the bars are about level with your saddle, that way you have a more comfortable semi-upright posture.

Or, sell both of your bikes and find one that is juuuuust right.