Actually, I had the same problem (unable to change line spacing) in Microsoft Student and Home Office. The problem is you can edit spacing, but the next time you open Word, it will be restored to the "Default" value of 10 pt spacing.
The fix is to:
- Select the Page Layout tab,
- Click the diagional down arrow below Line Spacing/Paragraph,
- In the Spacing area:
- - Change After from 10 pts to "0 pt",
- - Change Line Spacing from Multiple to "Single",
- Click <Default>,
- Click <OK>.
Yes, in this case, clicking "Default" makes your changes the New Default.
In the past and other places in Windows, selecting Default restores to the factory presets. That is not the case in Word/Office.