method 1
- home tab
- styles section
- click on the hidden arrow thing bottom right
- select 'No Spacing'
- 'No Spacing. is now added to the styles section
- make sure 'No Spacing' is selected
- click on 'Change styles / Set as Default'
double line spacing is now removed whilst maintaing office 2010 formatting
method 2
- home tab
- styles section
- Select 'Change Styles / Style Set / Word 2003'
- click on 'Change styles / Set as Default'
This changes formatting back to office 2003 styling, both line spacing and font + others etc..