1. You can publish any number of Playlists to signs. Each Playlist is assigned a Priority along with its schedule. Priority is NORMAL by default, however there are five priority levels: LOWEST, LOW, NORMAL, HIGH, HIGHEST.

2. Multiple playlists with NORMAL priority will play one by one in a continuous loop, in the order in which you saved each playlist on the website, oldest to newest (see 'Update Time' on the Playlists tab).

3. If you create another playlist and assign it a HIGH priority, only the HIGH priority playlist will appear on the sign until its schedule (if set) expires, at which point all playlists with NORMAL priority will resume playing. A playlist with HIGHEST priority will take precedence over a HIGH priority playlist, and so on. If multiple playlists with HIGH priority are published to a sign, they will play one by one in a continuous loop as described above.

4. To avoid the situation where your sign is unintentionally blank because there is a gap between playlist schedules, create and publish a playlist which is scheduled to play Forever, Every Day, All Day on Lowest Priority. 

See Scheduling a Playlist for step by step instructions.