In user user menu bar on the left side of the screen, click on APPS>Forms. 

Hover over the gear icon of the form you wish change the receiving email of.

Choose Notifications from the dropdown you see.

Click on the ADD NEW button.

In the SEND TO field, choose SELECT A FIELD.

In the SEND TO EMAIL field, choose EMAIL from the dropdown. This is the email of the person who filled out the form. This is how the system knows who to send this confirmation email to.

In the FROM field, put the name of your church.

In the FROM EMAIL field, you can put the main email of your church, in case they want to reply to it.

You can leave the rest of the fields as they are.