I'm using Pages 5.5.3 on OS X 10.10.4. I can't figure out how to change the size of the Body style for the entire document. If I try to increase the size of the Body text it only changes the size of the text where my cursor was last - the rest of the document is unaffected.
Thank you in advance.
When you click on the font size selector, an Update button appears beside the style you have selected:
Click on it and the style is updated to the new parameters. Existing and new text with this paragraph style will adopt them.