If the Media Gallery comments feature is enabled (see note below), users will be able to leave comments attached to the media items within your albums. Over time, these may build up and either clutter the album, or contain obsolete comments from previous users.
To automate the clearing of old comments:
Click on the module "Options" link, and select "Gallery Options".
In the resulting pop-up window, select the second option under the "Automatic Comment clean-up" section.
In the field provided, update the duration in days before the automated deletion routine is activated (e.g. leave it at '30' if you want comments older than a month to be deleted, or enter '365' if you want it to be comments older than a year).
Once you have made your selections, click the "Update Gallery" button to save your changes.