Choose actions for blank CD or DVD discs on Mac
When you insert a blank CD or DVD, a dialog may appear asking what you want to do with the disc.
On your Mac, insert a blank CD or DVD.
In the dialog that appears, do any of the following:
To specify what should be done with the disc, choose an action from the pop-up menu.
To have your Mac automatically perform the same action whenever a blank disc is inserted, select “Make this action the default.”
To continue without doing anything, click Ignore.
To cancel all actions and remove the disc, click Eject.
You can also use CDs & DVDs settings to set how your Mac responds when you insert a blank disc. To open these settings, choose Apple menu 
in the sidebar. (If you don’t have an optical drive connected to your Mac, CDs & DVDs settings aren’t available.)