You may first begin by adding a new card. If you require guidance ondoing so, you can find detailed steps here: How do I add a card?
Once you've added the card, proceed with the following steps:
1) Open your Atome app
2) Navigate to the ""Me"" section and select ""Payment Method.""
3) Choose the card you want to set as your primary card.
4) Simply toggle the switch to set the card as your primary. You'll know it's set when the toggle turns green.
It's important to note that each account must have a card marked as ""Primary,"" as all payments will be deducted from this card by default.