Hello Mark. Microsoft has recently updated the way "On this day" photo memories are shown in OneDrive. The new interface is a slideshow instead of showing the photo memories as an album. The new interface has limited functionality in that users are unable to navigate freely between photos, go back one photo or download a photo directly from memory. While there isn't an option to go back to the old way of arranging the photos, users may continue to look back through their historic photos by going to the OneDrive Photos page and filtering by photo date. If the slideshow is more irritating than helpful, you can turn off "On this day" by right-clicking the OneDrive icon in the taskbar, selecting Settings > Notifications and toggling off the memory alerts.
Best regards,