Rise: Default Font Size

In a course we are building, we are required to have a minimum font size of 18 for accessibility purposes.  Is there any way to set the default font size (not just default font)? What happens is even if we save templates with content at 18 pt, as soon as we paste (whether we use paste, paste special, or paste and match formatting) it always resorts to a 17 pt font.  This is very frustrating and can be time consuming for longer courses.  Any insight you can provide would be great!