How to change tooltip font size control in window form
this viedo will show you how to change your tooltip font size
//Should Change event OnPopup in your custom ToolTip control for dynamic tooltip size. Thank :)
private void OnPopup(object sender, PopupEventArgs e)
{
e.ToolTipSize = TextRenderer.MeasureText(this.GetToolTip(e.AssociatedControl), new Font("Khmer OS Content", 10F));
}