
Showing file will be marked by a special icons
or ![]()
By DoubleClick on file you'll change showing file.
You can also set time interval by clicking on 
- Append files to play list. You'll have to select one of two ways:

Files or Folder.
- Deleting items from play list. You'll have to select one of two ways:

Selected or Clear All.
or
- Play loop enabled or disabled.