To assign an index picture to an album, open the respective job and click on the Photo Management tab. On the album overview, select the album for which you want to assign the index photo and open it.
Click on the photo you wish to use as an index photo. A preview picture will open on the top right. Below this preview picture, you will find a star symbol, which is used to set the picture as the index photo. Once you click the star icon, the selected picture will show this icon:
Please note: Once a photo has been set as the index picture, it can only be replaced with another.