I found this impossible to do in the new layouts. The suggested screen options just aren't there. I went back to the classic layout and found it quite strightforward there (so long live the classic layout - it works so don't fix it) From the 'Wallet' page, bottom left hand corner 'Classic Site' > 'My Money' > 'Update' Select the card you want as default and 'Edit' > 'Make card primary' and save Note that if the CSC is not entered then the page is incomplete and the primary flag will drop out again.
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