Write's page margins, header and footer settings will not set to new defaults between sessions. Initially, page margins (default 2.0cm) seem to take but if header and footer settings are changed to new defaults and set with 'Apply' then when Write is reopened the original margins are reset to 2.0cm (0.79").
Environment and settings:
1. O/S: XP, sp3, 4GB RAM.
2. The location setting for this XP installation would normally default it to metric measurement but it was set to imperial/US measurement during installation (i.e. XP was installed in a country where 'metric' is the default but where O/S's measurement options were set to inches).
3. LibreOffice and OpenOffice before it have never respected the O/S's measurement settings (a bug in itself); they read the country code OK but always wrongly set the measurement settings to metric (cms) instead of inches ["]. After installation, the user then has to select imperial/US inch settings in the options. When this is done Writer's default margins of 2.0cm become 0.79".
4. When moving margins to the more usual British 1.0" (on all sides), the incremented stepper doesn't pass through exactly 1.0"*, so the user rounds up the margins to exactly 1.0" by tabbing through the settings selecting '1' each time. These are saved and LibreOffice reopened. (* Seems the calculation granularity or algorithm is a bit rough for not rounding properly during conversion--i.e.: so that it calculates or snaps through exactly 1.0", similarly tabs automatically convert to 0.49" instead of snapping to 0.5".)
5. The header and footer are then set to the same settings as in MS Office defaults (where header and footer are 0.5" from the paper edge). To ensure that exactly a 1.0" margin is kept, header/footer height and spacing from margin are set accordingly and saved with 'Apply'.
6. When LibreOffice 3.4 beta 5 is reopened the margins (on all sides) have defaulted back to 0.79" (2.0cm) and the header and footer which were defaulted to 'on' (ticked) have now reverted to 'off' (not selected).
Please refer to the Help / user list / forums to learn about how to set a template (with own page settings) as default :-)