What does setting a template as Active do?

If you check the active check box, your template will show in the list of available SMS Templates when selecting a MOBIT/SMS action from your campaign builder, depending on whether you select to plain text or MOBIT from the SMS Type check box as shown below.

What does setting a template as Double Opt in do?

If you check the double opt in check box, your template will show in the list of available Double Opt in SMS templates when selecting a MOBIT/SMS action as show below:

Why can't I edit or delete some of my templates?

You account comes preset with a certain number of templates that cannot be deleted. These will not have a check box to the left of their name and will prompt an error when you try to edit them.