no you cant globally affect any of the controls in the text generators WITHIN FCP
you can edit an XML file to change text controls.
you can try to do it yourself,
or use TItle Exchange from Spherico.
the free version does 50 at a time.
you could add a 3way colour corrector to the text generators, as Mark suggested,
if it;s only a dozen or so, the simplest approach is to make up one new title the way you want,
then edit that OVER all your existing text clips (Use the superimpose edit, to make this fast & simple.
then you go through and copy paste the text from your old generator into the new one.