You will receive a temporary authorization equivalent to $6.99 USD any time you add a payment card. This is to validate your credit or debit card. We make these authorization charges and then immediately invalidate them, so they'll be removed from your credit or debit card automatically (typically within one week). Please note, the voided charge will appear on your statement as a canceled charge versus a refund.
If the charge remains on your statement for longer than that, contact your bank to ask why the charge hasn't been removed even though it has been voided by Quora.