If you don't want your activity to be used as a template by others, you can disable this option after the activity has been created. Here's how:

1. Create your activity as usual

2. Once it's created, tap Edit activity 

3. In the editing screen, scroll down to find the Offer as template slider

4. Deactivate the slider

5. Your activity can no longer be copied by other users

Important: This setting can only be changed after the activity is created. As the creator, you will still be able to copy your own activity if needed.