Simple - How to Set a certain form as my starting project file

Question

I know it's so simple, but I'm a newbie and have tried to look thru whole designer environment but still cant find how to solve it .. The question is , If i have 2 or 3 form in a project (let's say form1, form2, and form3), how do i set a certain form (form2 for example) as my starting project after i build and run the program. From the menu bar, I tried the Project -> SetAs Startup Project function but seems it didnt work ... So can anyone help me out .. Thanks in advance ..