Switch Visa Cards come equipped with technology to enable customers to turn cards on and off easily right in the Switch Mobile App. This can be done on the Spending Screen. The Spending Screen is the middle tab on your bottom navigation bar and is represented by the block with outward pointing arrow icon 
.
When you first set up your card, this will be toggled to "off". Tapping the balance in the wallet cell will open that wallet for spending and turn the card "on". Once the card is turned on, it will turn dark blue and say "ON" to the left of the "Spend Wallet". To turn off again, simply click the "X" below the wallet balance. 