I am having a couple of problems with 3.5.3

I am unable to change the title box background color (in fact I can't change anything in this section, no matter what I put - font sizes for the text etc too in the next box down).

I am also unable to change the font size for the previous/next pages links.

Have I accidentally changed a setting somewhere that disables or over-rides this functionality?

Many thanks

What are you putting where?
What is the URL?
Do an export of your settings (ato->export/import settings) and attach to a reply