Manually edit the date a album/photo/video was created on.
EditCreation is a module for Gallery 3 which will allow users to manually edit the date which Gallery stores in the "created" field for each item.
This module may be downloaded from the Gallery forums here.
To install, extract the "editcreation" folder from the zip file into your Gallery 3 modules folder. Afterwards log into your Gallery web site as an administrator and activate the module in the Admin -> Modules menu. You will then be able to edit the creation date by selecting Edit from the Options menu.