By default the slideshow of PhotoChances will pick the images and the optional music randomly.
The program provides a method for controlling the order in which the program will pick the images and / or songs.
In the Images selection tab or in Music in the Settings window, there's a Sort option that additionally to Random offers "By name" and "By date created"
These sorting modes have the inconvenience that would produce always the same sequence of images or songs always starting with the same item. But this also provides a way to build a controlled presentation: Create a folder with the images each with a name numbered and set the Sort option to "By name".
Notice that you can save that configuration to a particular file so you can invoke it at any time, no matter if you restored the settings to a Random sorting.
More about saving options in independent files here.