Do any of the following:
Specify default AutoArchive settings for all Microsoft Outlook folders
AutoArchive is turned on by default. However, you can change its default settings.
Note If you change the archive file listed under Move old items to, it's changed for all folders that use the default AutoArchive settings.
Specify AutoArchive settings for individual folders
To archive to a file other than the default one, specify a different file name in the Move old items to box. The next time AutoArchive runs on this folder, Outlook will automatically create the new archive file for items in this folder.
Note To archive to a file other than the default one, specify a different file name in the Archive file box. Outlook automatically creates another archive file for items in the selected folder.