Change Outlook Cache Setting in Classic Outlook

Within Outlook, go to File > Account Settings > Account Settings.

Go to the E-mail tab, then select Change.

Select the time frame you would like to have cached, and then Next/Finish out of this dialog box.

Close and re-open Outlook. This will re-configure your cache.

It will take some time for your Outlook to re-build your local cache, but you can start using it right away.