How Can I Add New Component Gravity Which Is Not Given In Default Game Play Type.

How can i add new component gravity which is not given in default game play type.My aim is to make ball bounce when it fall on a trampoline or any similar object like that in portrait mode. Even though I am adjusting bounce force it's not working so who can I add gravity to make ball fall and then bounce.

 

If this is with reference to BB3, you can change the gravity of the world by going to the mind map and selecting the world.
To add a bounce force add a movement node ( jump / bounce ) for the character and if collide node ( by selecting the platform from which you want the character to bounce ) and connect both of them.