Jenkins will try to create cloud service with template name or will use if one exists already with same name. If you want to use a different cloud service , use advanced section and define cloud service that needs to be used for this template.

Rules for template name
1.Cloud service name must start with a letter or number, and can contain only letters, numbers, and the dash (-) character.
2.Every dash (-) character must be immediately preceded and followed by a letter or number; consecutive dashes are not permitted in container names.
3.Cloud service name must be from 3 through 63 characters long.