First if you want to play them every night, set date off, disable weeks also. Days of the week all is OK
Your settings start the event at 6, but it never stops, the same for 18 hour.
You need to load new tracks at the hour these tracks are not allowed to play.
For exmaple the selected tracks start at 6 or 18 and you wnat to play then for only 1 hour you need to laod new tracks at 7 eg.19 hour or if you do not want to play there any tracks send a stop command
so in thies case start at 6 next hours start other events with other tracks same for 18
The settinge now sttart the event at 6 and play whole day untill 18 where you set the new event, the event from 18 runs whole night until 6 in the morning