Each deposit and withdrawal of cryptocurrency to and from your Blockchain Exchange trading account requires a network fee. If you are sending crypto from your Blockchain Wallet to Blockchain Exchange, you are free to set this fee to your liking by selecting a regular or priority fee when sending. Deposits will be registered to a trading account after ten network confirmations. Keep in mind that selecting the regular fee (which is at a lower cost to you than a priority fee) may result in your deposit remaining unconfirmed for a long time, or be rejected. As with all cryptocurrency transactions, fees are collected by the miners who confirm transactions, not Blockchain.
For withdrawals from your Blockchain Exchange account, your transaction will automatically include an appropriately sized network fee to get your withdrawal confirmed and your funds available in a timely manner. This fee cannot be changed.