You are not doing things properly.
The MainMenu form is already created inside the FormChangeControls\MainMenuDriven folder and all you have to do is set it as the startup form, possibly add a driver to it, add as many MainMenuButtons as the forms you want to control and make sure to setup each button to open the corresponding form (provided that these forms have already been added to the project).
When you are trying to do things you haven't done before then you always use either a copy of your existing solution or a fresh solution.
This way, instead of trying to correct errors, you just discard the solution and start all over again.