# Setting default font size [duplicate]

Say I want to create a new stylesheet that would be based on some preexisting stylesheet. The first thing I'd like to do is to set some initial font size globally by:

Cell[StyleData[All], FontSize->12]


However, I can now no longer change the size of any cell (although it appears to change in stylesheet editor it doesn't in the notebook). In other words, this no longer works:

Cell[StyleData["Title"], FontSize->22]


What am I doing wrong and why?