If you want a service or service set to “belong” to a host template, you can add the service or service set directly to the host template.
You could also add a host group to you template and you that in an apply rule.
Same goes for a host variable you add to the template and use that to apply services.
I went to Icinga Director -> Hosts -> Templates -> Clicked on One Template where I want to distribute Single Service -> Right Side Service -> Add Service
In the drop down - it is not single service - rather it is all service templates. I want to add single service and not service template. You see the existing ones are Single Service and Not Service Template