A common question is why some content will randomly start playing first even though it is not ordered first in a playlist. This is due to apps that run on what is called variable duration.
If you have content with variable duration in the playlist then ScreenCloud will play that content first. This is normal behavior on Signage as it was designed to support syncing multiple screens. Examples of apps that use variable duration are Google Slides and Vimeo. You will be prompted which apps have variable duration when adding them into a playlist.
Our team is working on improving signage functionality for this in the future.