Ho to set Font Family in word Document

I am using below code but not working.

Aspose.Words.License license1 = new Aspose.Words.License();
license1.SetLicense("Aspose.Total.lic");
Aspose.Words.Document tempDoc = new Aspose.Words.Document();
Aspose.Words.DocumentBuilder builder = new Aspose.Words.DocumentBuilder(tempDoc);
builder.Font.Size = 8F;
builder.Font.Bold = true;
builder.Font.Name = "Impact";
// builder.Font.Size = 24F;
// Aspose.Words.Fonts.FontSettings.DefaultInstance.SubstitutionSettings.DefaultFontSubstitution.DefaultFontName = "Arial Unicode MS";
builder.PageSetup.Orientation = Aspose.Words.Orientation.Landscape;
var docStructures = new StringBuilder();
StringBuilder bindMultipleGrid = new StringBuilder();
StringBuilder bindTableDesc = new StringBuilder();

@Karthimani If you would like to set default document font, you can use StyleCollection.DefaultFont property.
If this does not help, please elaborate your problem in more details and provide the current and expected output documents.