My first thought is to question if you have set any "styles". Reference: http://www.shaunakelly.com/topic/word/styles.

For example, if you had each line mention created with a 'style' of "Body Text" with the text 'justified' and then you hit the return, the following line does not retain the same "style" (body text) as the previous line but, reverts to the style of 'normal' (where the text may be defaulted to align left (or, left justified).

So, in a nutshell, check your styles (if you have actually created the file with 'styles'. If you have not, you may consider doing so).