You have a default wallet for each coin available. This is the wallet that will automatically be used whenever you select a specific coin for an order.
Because we allow multiple wallets for each currency, there may be circumstances when you wish to change the default wallet settings for a particular currency. To do this, open the My Wallets page by selecting it from the drop down menu under your account name in the upper right hand corner of the screen.
On the left hand side of the screen, select the currency which you wish to set the default wallet for and click on the + icon next to it to expand the list of wallets you currently have for that currency.
Once you have done this, towards the right side of the screen under the column "Is Default" you will see switch options for any wallets you have of that currency.
Clicking on the blank side of any of the switches that currently reads "No" will bring up a confirmation message.
If you have 2FA enabled, you will need to enter a code before confirming this change. Once you have confirmed the change, any order you place involving that currency will automatically default to withdrawing or depositing using that wallet.