Before you start evaluating single images it is important to make sure that your rounds or collections are se set to "Individual images" at "Content to be evaluated". This also applies to the creation of single image collections. Learn how to create a single image collection here.
Start from "All Submissions" without any prior rounds created and follow these steps for single image evaluation:
Select "All submissions" from the sidebar menu.
Switch the viewing mode to "List submissions by images". The option for this is in the top right corner
Click on Setup in the top right corner
Select content to be evaluated: "Individual Images"
Either add individual images to the round, or add all submissions by checking the box
Select an evaluation mode that suits your needs
Invite your Jury
Start evaluating your submissions