When an image file is changed or overwritten, it will be marked as 'outdated' by InDesign. This is to bring attention to the designer that the image may have changed.

By default, this box is not checked, and users must manually update any 'outdated' images when they open a document within one2edit.

Checking this box, however, means that any 'outdated' images will be automatically updated within a document when that document is next opened in one2edit. This updating will be done silently, without any need for user interaction.