If you use the Format Text dialog box, you will find there is a Save…
Vectorworks Tip #164 – Text – Use Text Styles with Classes
One of the new features with Vectorworks 2015 is the ability to link a class to a Text Style. This gives you a similar control to controlling the graphic style of objects with a class. When you assign your text to a class it will automatically use the text style assigned. This is such an improvement when you have areas of text that have to be on different classes and at different sizes.