Create a new style, you can name it whatever you like, I chose MONO, You should set the style up like any of your other styles, Choose which font, default height, underlay, density etc... then save it
Decor Number
This is the Decor number from the drop down in lettering. You can refer back to the lettering or, you can simply try different numbers and preview until you find the one you like
Alignment
The alignment must be set to Build in, in order for the system to know that the decors are built into the font style and not separate like normal decors