Hello!
I've downloaded the program and I opened it. Yes, it is completely possible to edit your application, or that window. However, I'm not fully sure about you'd like to stick to the original exe file. Since I can just make a new windows form application, which will be much easier to edit and add features to in the future. This way your application can be upgraded over time. Please let me know if you are interested.
Best regards, Patrik Takacs.