To adjust or set up a default bet type or bet amount on the desktop site click on the person icon to open the Your Account menu and then select Preferences from the resulting drop-down menu.
From here you can view if bet confirmation is on or off and change it by clicking the Request bet confirmation box indicated below. If the box is empty, bet confirmation is off. If it has a checkmark, bet confirmation is on.
Your Default bet type can be changed by selecting the blue dropdown arrow and clicking on your desired wager type. 
Under Default bet amounts you can select either to set a single default bet amount or a default bet amount for each wager type by clicking your preferred circle. A blue circle with a white center means the option is selected, while a white circle indicates the option is not.
From there you can set your default bet amounts by clicking and typing into the box to the right of your chosen option. If you have previously set limits for a specific bet type you will also see those in that box otherwise, it will default to Minimum amount.
Once you have set your default wager type and amount, these selections will auto-fill all future placed wagers. You are still able to adjust the individual wager type and amount while placing your wager, but your chosen preset settings will be your default wager settings.
For Help with Default Bets and Wager Confirmation on Mobile, Click Here!