As I've already said, paragraph formatting is controlled via paragraph Styles. If some paragraphs are giving differrent spacing than others, that's most likely because they're using different paragraph Styles. If you want to make all lines single-spaced, the correct way to do this is by modifying the underlying Styles, which the links I posted in your other thread show you how to do. In Word 2010, the default paragraph Style (Normal) uses an 11pt Calibri font, left-aligned text, a 1.15 time multiple line spacing (which gives 12.65pt), 0pt before and 10pt after paragraph spacing. If you want to change that Style for all new documents, see:
http://office.microsoft.com/en-us/wo...001121028.aspx
If you don't like Word's use of Styles and the other features it provides, perhaps you should use WordPad for the bulk of your work, at least - it's free and comes with Windows.