I may be wrong but I think there are a few things that do not work the way they should.

The first:

 

I type a line of text or a paragraph. I could set a phrase inside the paragraph to a different font size.  I later realize that it does not look well and I try to change the whole paragraph to a new size. I select the paragraph, change the font size to size 3 (for example) and the editor only changes the outside. The inner phrase does not inherit the changes, and it should. Am I wrong?