Originally Posted by ksg
I agree that it is far from intuitive. And as for removing all styles and starting over, it's often not possible to do that: my experience is that if an outline originated as a .rtf file, for example, it seems to inherit some fonts and sizes and weights that you have to change one entry at a time. Tedious hardly begins to describe it. Just Selecting All and setting the font doesn't seem to work.
So one thing that might not be clear to everyone is that the styles have a hierarchy structure. Explained in the help file under "Style hierarchy". What is likely happening when you import/paste text that has formatting applied to it, is that those styles are brought in as applied on one of the top two levels depending on the format.
Styles defined in one level of the hierarchy will overwrite any conflicting styles of the levels below it. So if you had font size 14 applied to the whole document and then applied font size 8 at text insertion, the text would be size 8.
You can see the style attributes and the hierarchy of the selected text in the Style Attributes inspector. Styles at the top of the list overwrite styles below if they conflict.
This is how all other style systems I can think of work in general, you just might not see the hierarchy laid out for you.
What I think confuses people is when you want to overwrite existing styles in groups instead of adding to the current style.
A simple way to erase any styles that you brought in with text is to highlight those rows and then Format -> Clear Style.
It is possible to apply a style and have it complete overwrite all style of the same level and below. You can do that by dragging the style from the style palette and hold down the command button. (You will notice if you don't hold down the command button, a plus sign will appear indicating you are adding that style) This won't however overwrite styles applied above that level, in this case, the text insertion level.
I understand parts of this functionality can prove confusing at first, but it is quite logical to me anyways. What you want to avoid doing is applying styles at the text insertion level if possible as should you decided you want to change them all, it could prove tedious. The style system is powerful if used properly.