Change Form as the main Form to run, making it easy to test the functionality of each Form separately. This tutorial will show you how to set default form in Visual Studio using VB.NET

Assuming you have multiple Form, you want to set a default Form as the main Form you can do as follows

Right-click on your project in solution explorer->Choose properties->Select the Application Tab

select default form in

Select the form that you want to set as the main Form the Dropdown under 'Startup form'

In C# windows forms we just need to change the Form that we want to set as the main Form in the Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace csharpcode
    static class Program
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        static void Main()
            Application.Run(new frmMain());